(standard-latex-block-names): Add "math".

(standard-latex-block-names): Add "math".
(latex-mode): Tweak tex-*-(head|trail)er regexps.
Tweak paragraph regexps to allow a leading [ \t]*.
(tex-latex-block): Insert a newline if necessary.
(latex-insert-item): Only insert a newline if necessary.
(tex-guess-main-file): New function.
(tex-main-file): Use it.  Add arg `realfile'.  Trim `.tex'.
Set tex-main-file if TeX-master is provided.
(tex-latex-indent-syntax-table): Map ( and ) to punctuation.