composite and paint ops

[Patrick Julien]

Boudewijn,

	The implementation strategy for composite and paint ops could quickly 
degenerate to an explosion of classes for even simple functionality.

	Consider having paint and composite opts has simple members of KisPainter.  
The color space strategies, combined with latest suggested improvements, 
would expose enough information to do this from KisPainter.

	The methods could even be static, however, not sure yet that would be a good 
idea.