* src/getargs.h (trace_e): Add trace_scan, and trace_parse.

* src/getargs.c (trace_types, trace_args): Adjust.
* src/reader.c (grammar_current_rule_prec_set)
(grammar_current_rule_dprec_set, grammar_current_rule_merge_set):
Standardize error messages.
And s/@prec/%prec/!
(reader): Use trace_flag to enable scanner/parser debugging,
instead of an adhoc scheme.
* src/scan-gram.l: Remove trailing debugging code.

src/getargs.c

@@ -52,6 +52,8 @@ static const char * const trace_args[] =
   /* In a series of synonyms, present the most meaningful first, so
      that argmatch_valid be more readable.  */
   "none       - no report",
+  "scan       - scanner traces",
+  "parse      - parser traces",
   "automaton  - contruction of the automaton",
   "bitsets    - use of bitsets",
   "grammar    - reading, reducing of the grammar",
@@ -66,6 +68,8 @@ static const char * const trace_args[] =
 static const int trace_types[] =
 {
   trace_none,
+  trace_scan,
+  trace_parse,
   trace_automaton,
   trace_bitsets,
   trace_grammar,