Trim inline code. Fixes #69.

The inline code regex itself could also simply have \s* prepended
and appended to outside the main capture. However, this results
in less accurate behavior.
add configurable -lang prefix. closes #67 and #54.
fix options merge.
better inline code trimming. avoid so many newlines after paragraphs. closes #103.
this is faster than just cap[1] for some reason.
ignore angle brackets in ref links. fixes #101.
move vertical bar escape to gfm only.