cappuccino/cappuccino — pull request #1524 by stewa (2012-04-26 21:31:23+00:00)
Title: Fix for issue #1499: wrong placeholder string in CPTextField

- Introduced _CPStateMarker class for markers. Previous NSString markers could have been valid values.
- Removed CPNullMarker. There's no NSNullMarker in Cocoa.
- Moved marker handling to subclasses in CPTextField, CPImageView, CPColorWell and CPCheckBox
- Changed CPColorWell placeholder color to black to match Cocoa.