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