Fix a small bug in macro

Fix header indentation in the symbol list (Fixes SublimeText-Markdown…

…#150)

Merge branch 'v2.0.5'

Merge branch 'v2.0.4'

Highlight plain URIs and emails

Improve README

Make bold and italic markers configurable

Update README and changelog

Another attempt at st3 compatibility

Hopefully adding to ST3 package control