Move pats options and :LatexTOC out of mappings.vim

Both are now in motion.vim, at hopefully appropriate places.

- the pats options move into the `FindMatchingPairs` functions as that
  is the only place they were used.
- The `:LatexTOC` command is added right at the end, similarly to the
  `:Latexmk*` commands in latexmk.vim.
Moved pats options to top level
Merge pull request #70 from runiq/pats_and_toc

Move pats options and :LatexTOC out of mappings.vim
Add :LatexTOCToggle command to toggle TOC display
Merge pull request #71 from runiq/toggle_toc

Add :LatexTOCToggle command to toggle TOC display