Platform: extensible welcome wizard:
* themes page can be customized
* additionas UI setting supported
(cherry picked from commit 7283476)
IDEA-128476 UI of Customize IDE wizard is broken after theme change
(cherry picked from commit b5c02da)
OC-10346 AppCode marks available API as not available for deployment target 10.10
(cherry picked from commit 01d3aed)
CR-OC-1970
(cherry picked from commit 4ae41f7)