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

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.