Use %%error_verbose.
(yyparse): Likewise.
* src/output.c (prepare): Give its final value.
* src/muscle_tab.c (muscle_init): Init new muscle 'error_verbose'.
* src/getargs.h: Add its extern declaration.
* src/getargs.c (error_verbose_flag): New int.
(getargs): Update to catch new case.
* src/options.c (option_table): 'error-verbose' is a new option.
(shortopts): Update.