Create CEThemeManager class
Add theme menu to main menu
Add default key

Conflicts:
	CotEditor/Sources/constants.h
Create CETheme class
Rename cursorColor to insertionPointColor
Use binary format for theme plist
Add copy keyword to properties whose type has also mutable version
Fix themeManager
Improve CETheme class
Use theme setting for coloring
Add theme menu to main menu
Draw page guide programmically
Redraw also selected line on theme changing
Theme editor (WIP)
Theme name validation
Implement error handling for theme edit
Implement text view redraw with theme update
Add easy initializer to CETheme class
Define notification userInfo keys for theme update
Implement restore bundled theme