variables: use parse.assert' instead of debug'.

* src/getargs.c (getargs): Map -t to %define trace.parse.
	* src/scan-gram.l (%debug): Map to %define trace.parse.
	* data/bison.m4 (b4_percent_define_if_define): Map `.' in variable
	names to `_' in macro names.
	(b4_debug_if): Replace with...
	(b4_parse_trace_if): this.
	* data/glr.c, data/glr.cc, data/lalr1.cc, data/lalr1.java,
	* data/yacc.c: Adjust.
	* doc/bison.texinfo (Decl Summary): Document %debug as obsoleted.
	Use @code to label the variable list.
	Document the variable parse.trace.
	(Tracing): Promote the parse.trace variable.
	* TODO: %printer is not documented.

src/getargs.c

@@ -288,7 +288,8 @@ Parser:\n\
   -L, --language=LANGUAGE    specify the output programming language\n\
                              (this is an experimental feature)\n\
   -S, --skeleton=FILE        specify the skeleton to use\n\
-  -t, --debug                instrument the parser for debugging\n\
+  -t, --debug                instrument the parser for tracing\n\
+                             same as `-Dparse.trace'\n\
       --locations            enable location support\n\
   -D, --define=NAME[=VALUE]  same as `%define NAME \"VALUE\"'\n\
   -p, --name-prefix=PREFIX   prepend PREFIX to the external symbols\n\
@@ -616,7 +617,8 @@ getargs (int argc, char *argv[])
 	break;
 
       case 't':
-        muscle_percent_define_insert ("debug", command_line_location (), "");
+        muscle_percent_define_insert ("parse.trace",
+                                      command_line_location (), "");
 	break;
 
       case 'v':

src/scan-gram.l

@@ -175,7 +175,7 @@ splice	 (\\[ \f\t\v]*\n)*
 {
   "%binary"                         return PERCENT_NONASSOC;
   "%code"                           return PERCENT_CODE;
-  "%debug"                          RETURN_PERCENT_FLAG("debug");
+  "%debug"                          RETURN_PERCENT_FLAG("parse.trace");
   "%default"[-_]"prec"              return PERCENT_DEFAULT_PREC;
   "%define"                         return PERCENT_DEFINE;
   "%defines"                        return PERCENT_DEFINES;