current support for latex fragments was inline only, i.e. lines containing block
elements (e.g. a line starting with `* `, i.e. a headline) will not be parsed
as part of the latex fragment but the respective block element. Parsing latex
blocks at the block level should fix that. Note that in any case we don't do
any processing and just emit the raw latex (leaving the rendering to e.g. js).
All tags are put on a line by themselves to help with visual
diffing. Apparently this extra cosmetic whitespace causes problems inside p
tags for ppl who want to use `white-space: pre`. Not much hurt for visual
diffing in removing cosmetic whitespace for just p tags and can't think of
anything that would break because of this right now. So let's do it and wait
for things to break.
delimiters are not always 2 in length - $ being the exception. Also we have to
make sure to handle both $ and $$ delimiters.
Not proud of this solution but can't think of anything simpler right now - will
come back to this later hopefully.
