Code refactor

CPLayoutEngine: renames suggestValues -> suggestSize
Added: suggestOrigin:forItem:
CPView: Added suggestFrameOrigin: and suggestFrameSize:
Disable -fittingSize in contentSizeConstraints calculation.

Re-enable when fittingSize is implemented correctly.
Add -intrinsicContentSize in various controls with the correct default hugging priorities.

CPSlider, CPStepper now support size constraints.
Code style