Dollar signs not handled the way Pandoc handles them

[alerque]

As noted in discussion on PR #280 Pandoc has some logic for guessing when dollar signs to not mean math: namely the trailing close marker has to be preceded by non-whitespace.

The same logic does not appear to be working properly in our syntax highlighting.

[protist]

I'm testing out vim-pandoc-syntax as an alternative to vimwiki. One of my main irritations is over-interpretation of $ in vimwiki. Pandoc is indeed "smart" with this, correctly parsing something like the price increased from $1 to $2 during conversion. However, vim-pandoc-syntax incorrectly parses the section between the dollar signs (1 to ) as a math block, and displays this section wrong.