Convert underscores to dashes in some %define variable names.

For now, just api.push-pull and lr.keep-unreachable-states.
Maintain old names for backward compatibility.
* NEWS (2.5): Document.
* data/c.m4 (b4_identification): Update comment.
* data/yacc.c: Update access.
* doc/bison.texinfo: Update.
* etc/bench.pl.in (bench_grammar): Update use.
* src/files.c (tr): Move to...
* src/getargs.c, src/getargs.h (tr): ... here because I can't
think of a better place to expose it.  My logic is that, for all
uses of tr so far, command-line arguments can be involved, and
getargs.h is already included.
* src/main.c (main): Update access.
* src/muscle_tab.c (muscle_percent_define_insert): Convert old
variable names to new variable names before assigning value.
* src/reader.c (reader): Update setting default.
* tests/calc.at: Update uses.
* tests/conflicts.at (Unreachable States After Conflict
Resolution): Update use.
* tests/input.at (%define enum variables): Update use.
(%define backward compatibility): New test group.
* tests/push.at: Update uses.
* tests/reduce.at: Update uses.
* tests/torture.at: Update uses.

doc/bison.texinfo

@@ -4561,7 +4561,7 @@ valid grammar.
 @subsection A Push Parser
 @cindex push parser
 @cindex push parser
-@findex %define api.push_pull
+@findex %define api.push-pull
 
 (The current push parsing interface is experimental and may evolve.
 More user feedback will help to stabilize it.)
@@ -4577,10 +4577,10 @@ within a certain time period.
 
 Normally, Bison generates a pull parser.
 The following Bison declaration says that you want the parser to be a push
-parser (@pxref{Decl Summary,,%define api.push_pull}):
+parser (@pxref{Decl Summary,,%define api.push-pull}):
 
 @example
-%define api.push_pull "push"
+%define api.push-pull "push"
 @end example
 
 In almost all cases, you want to ensure that your push parser is also
@@ -4591,7 +4591,7 @@ what you are doing, your declarations should look like this:
 
 @example
 %define api.pure
-%define api.push_pull "push"
+%define api.push-pull "push"
 @end example
 
 There is a major notable functional difference between the pure push parser
@@ -4640,14 +4640,14 @@ for use by the next invocation of the @code{yypush_parse} function.
 
 Bison also supports both the push parser interface along with the pull parser
 interface in the same generated parser.  In order to get this functionality,
-you should replace the @code{%define api.push_pull "push"} declaration with the
-@code{%define api.push_pull "both"} declaration.  Doing this will create all of
+you should replace the @code{%define api.push-pull "push"} declaration with the
+@code{%define api.push-pull "both"} declaration.  Doing this will create all of
 the symbols mentioned earlier along with the two extra symbols, @code{yyparse}
 and @code{yypull_parse}.  @code{yyparse} can be used exactly as it normally
 would be used.  However, the user should note that it is implemented in the
 generated parser by calling @code{yypull_parse}.
 This makes the @code{yyparse} function that is generated with the
-@code{%define api.push_pull "both"} declaration slower than the normal
+@code{%define api.push-pull "both"} declaration slower than the normal
 @code{yyparse} function.  If the user
 calls the @code{yypull_parse} function it will parse the rest of the input
 stream.  It is possible to @code{yypush_parse} tokens to select a subgrammar
@@ -4664,8 +4664,8 @@ yypstate_delete (ps);
 @end example
 
 Adding the @code{%define api.pure} declaration does exactly the same thing to
-the generated parser with @code{%define api.push_pull "both"} as it did for
-@code{%define api.push_pull "push"}.
+the generated parser with @code{%define api.push-pull "both"} as it did for
+@code{%define api.push-pull "push"}.
 
 @node Decl Summary
 @subsection Bison Declaration Summary
@@ -4887,8 +4887,8 @@ Some of the accepted @var{variable}s are:
 @item Default Value: @code{"false"}
 @end itemize
 
-@item api.push_pull
-@findex %define api.push_pull
+@item api.push-pull
+@findex %define api.push-pull
 
 @itemize @bullet
 @item Language(s): C (deterministic parsers only)
@@ -4968,8 +4968,8 @@ without performing any extra reductions.
 @end itemize
 @end itemize
 
-@item lr.keep_unreachable_states
-@findex %define lr.keep_unreachable_states
+@item lr.keep-unreachable-states
+@findex %define lr.keep-unreachable-states
 
 @itemize @bullet
 @item Language(s): all
@@ -5467,8 +5467,8 @@ exp: @dots{}    @{ @dots{}; *randomness += 1; @dots{} @}
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypush_parse} to parse a single token.  This
-function is available if either the @code{%define api.push_pull "push"} or
-@code{%define api.push_pull "both"} declaration is used.
+function is available if either the @code{%define api.push-pull "push"} or
+@code{%define api.push-pull "both"} declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
 @deftypefun int yypush_parse (yypstate *yyps)
@@ -5485,7 +5485,7 @@ is required to finish parsing the grammar.
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypull_parse} to parse the rest of the input
-stream.  This function is available if the @code{%define api.push_pull "both"}
+stream.  This function is available if the @code{%define api.push-pull "both"}
 declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
@@ -5501,8 +5501,8 @@ The value returned by @code{yypull_parse} is the same as for @code{yyparse}.
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypstate_new} to create a new parser instance.
-This function is available if either the @code{%define api.push_pull "push"} or
-@code{%define api.push_pull "both"} declaration is used.
+This function is available if either the @code{%define api.push-pull "push"} or
+@code{%define api.push-pull "both"} declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
 @deftypefun yypstate *yypstate_new (void)
@@ -5520,8 +5520,8 @@ allocated.
 More user feedback will help to stabilize it.)
 
 You call the function @code{yypstate_delete} to delete a parser instance.
-function is available if either the @code{%define api.push_pull "push"} or
-@code{%define api.push_pull "both"} declaration is used.
+function is available if either the @code{%define api.push-pull "push"} or
+@code{%define api.push-pull "both"} declaration is used.
 @xref{Push Decl, ,A Push Parser}.
 
 @deftypefun void yypstate_delete (yypstate *yyps)
@@ -8929,7 +8929,7 @@ and @code{%define api.pure} directives does not do anything when used in
 Java.
 
 Push parsers are currently unsupported in Java and @code{%define
-api.push_pull} have no effect.
+api.push-pull} have no effect.
 
 @acronym{GLR} parsers are currently unsupported in Java.  Do not use the
 @code{glr-parser} directive.