Optimised images
Support for resizing windows on all sides
Finished full window resize support

- The main run loop resets the cursor if it falls outside of all windows during a mouse move.
- Added cursors supported by CSS that are not in NSCursor.
- Code cleanup in CPCursor.
- Cursors now indicate available resize directions if there is a window min/max size.
- Reduced slop to 3, what it is in Cocoa.
- Added a second non-min/max window to the demo.
Merge pull request #1708 from imageoptimiser/optimised-images

Optimise images (94 KB reduction)
Fixed: CPPanel could not always become the key window.

Without this fix, `CPPanel` followed the same rules as `CPWindow` with regards to becoming the key window. But `CPPanel` is supposed to always be willing to become the key window, as stated in its documentation.

This change makes `CPPanel` always return `YES` for `canBecomeKeyWindow`.
Merge branch 'refs/heads/window-resize' into slevenbits
Merge branch 'refs/heads/master' into slevenbits
Merge remote-tracking branch 'Slevenbits/master' into slevenbits-master