Atom with quotes

`:"string"` and `:'char list'`
Atom literals
Atom highlighting
Ensure JDK 1.6 compatibility
Test operator atom lexing
Make superclass ParsingTests abstract

Make classes that don't have tests themselves abstract.
Add parsing test to cover all operator atoms
Add operator atom to Color Setting page
Merge branch 'feature/4/atoms'
Update changelogs and version

Closes #4

Update plugin change, CHANGELOG.md for v0.1.2, atoms.