Allow delete char '~' to be escaped.
Add insert and progress bar extension

- Add insert tags with ^^test^^
- Add progress bar with [==40% “Optional Label”] or [==20/500 “Optional
Label”]
CSS additions and changes

- Add progress bar CSS (also optional animated progress and gloss class)
- Use a different color for selections that doesn’t conflict with mark
tags
- Insert tags use traditional underline text decoration
Update test text
Adjust progress gloss
Add admontionicon extension

- Add icon spans to admonition divs
CSS update

- Add question admonition
- Change caution admonition to orange
- Change note admonition to yellow
- Default admonition is gray
- Add a stripped down font awesome for admonition icons
- No progress bar box-shadows in print
- Organize some CSS
Update admonition test
ST2 fix for etree iter
CSS cleanup
Fix typo of setting name
Update reamde
Fix progress bar section's anchor link
Merge pull request #231 from facelessuser/master

New Extensions and Modifications