Backwards-incompatible strikethrough changes

Fix vint

Don't `set cpo&vim` if we're going to early exit

Fix regex to match emphasis with alpha at end (#372)

Fix skip in pandocReferenceLabel to work with bracket in code in ref and add test

Fix highlighting with code in links in lists

Apply fixes from syntax upstreamed in VIM (#393)

Enable spell check in pandocDefinitionBlock

Fix code typo, disable spell check in pandocAmpersandEscape

Skip loading syntax/pandoc.vim if it's loaded (#397)

Bump python version so linter works again (#398)

Syntax highlighting for ```{=language} ... ``` code blocks (#369)

Add an autocommand to re-add highlight groups (#388)

Add the ability to disable inline math (#378)

Correctly highlight links without suffix (#380)