v0.3.0

This is a major release with breaking changes...

• BREAKING Changed disableOnEdit to disable-on-edit
• BREAKING Remove hyphen limitation on key names
• BREAKING Move to using mods within themes without -global-mod suffix
• Fixed update theme action to refresh styles
• Pre-check mod variables when loading instead of at mod time
• Improved performance when adding style elements
• Add display: none on style elements
• Updated README