Custom delimiters (use a character other than '$') about doctemplates

[PerpetualCreativity]

If anyone is curious, I've added this functionality to my fork of doctemplates. I only had to touch Text.DocTemplates.Parser. There's only a couple places where the string or double delimiter string versions are used, so I ended up only adding one field to PState (the Char delimiter). It still passes all tests, and as far as I can tell there's no difference in performance according to the benchmarks.

[jgm]

out of curiosity, what character are you preferring to use as a delimiter instead of $ and why?

[PerpetualCreativity]

Hi! I wanted to do what you suggested here but I have the issue that $ is also used in Pandoc Markdown for math (and $$$$ for display math gets pretty ugly).

I was thinking of using %. I'm writing a static site generator using Pandoc and DocTemplates and would probably want to let users customise this, though.

I realise this is probably not the intended use of DocTemplates.