* src/getargs.c (longopts): Support `--output'. getopt is now

* src/getargs.c (longopts): Support `--output'.  getopt is now
able to understand that `--out' is OK: the two racing long options
are aliases.
(usage): Adjust.
* src/lex.h (tok_setopt): Remove, replaced with...
(tok_intopt, tok_stropt): these new guys.
* src/lex.c (getopt.h): Not needed.
(token_buffer, unlexed_token_buffer): Not const.
(percent_table): Promote `-' over `_' in directive names.
Active `%name-prefix', `file-prefix', and `output'.
(parse_percent_token): Accept possible arguments to directives.
Promote `-' over `_' in directive names.
* doc/bison.texinfo (Decl Summary): Split the list into
`directives for grammars' and `directives for bison'.
Sort'em.
Add description of `%name-prefix', `file-prefix', and `output'.
Promote `-' over `_' in directive names.
(Bison Options): s/%locactions/%locations/.  Nice Freudian slip.
Simplify the description of `--name-prefix'.
Promote `-' over `_' in directive names.
Promote `--output' over `--output-file'.
Fix the description of `--defines'.
* tests/output.at: Exercise %file-prefix and %output.