(TeX_commands): Skip comments.

(TeX_commands): Skip comments.
(TEX_defenv): Now contains more contructs.
(TEX_cmt): Make it a static char and move it before TeX_commands.
(TeX_commands): Shorten the tag to the brace after the name.
(TeX_commands): Names now include the initial backslash.
(TeX_commands): Names do not include numeric args #n.
(TeX_commands): Correct line char number in tags.
(TEX_tabent, TEX_token): Deleted.
(TeX_commands, TEX_decode_env): Streamlined.