Fix symbol, \url, macro, paragraphs in LaTeX format. Fix #117
Fix symbol, \url, macro, paragraphs in LaTeX format. Fix #117

* Don't replace symbols like ` and ' inside HTML tags (via new inTag).
* Now we can support " like LaTeX does (equivalent to '').
* Escape (latexEscape) verbatim and \url argument in text from LaTeX processing.
* Fix paragraph handling: \n\n converts to \par before other stuff;
  then macros can correctly consume newlines; and merge multiple <p>s.
* Replace macros more efficiently, and repeatedly until no more expansion
  (important for \let in particular).
* Support \c{z}.

edemaine/coauthor,edemaine/coauthor