[[ ThreadedRendering ]] Implemented pthread thread pool.
[[ ThreadedRendering ]] Split mac redraws into 4 tiles, each of which is rendered in it's own thread.
[[ ThreadedRendering ]] Initial implementation of windows thread pool.
[[ ThreadedRendering ]] Initial implementation of iOS, Linux and Android threaded rendering.
[[ ThreadedRendering ]] Updated stack tile creation and rendering to platform indapendent level.
[[ ThreadedRendering ]] Put locks around stack id cache access.
[[ ThreadedRendering ]] Fixed minor bug in legacy gradients.
[[ ThreadedRendering ]] Updated Mac platform surface to use single backing buffer.
[[ ThreadedRendering ]] Updated region clipping to make sure all platform stack surfaces clip correctly.
[[ ThreadedRendering ]] Fixed issues with image locking.
[[ ThreadedRendering ]] Implemented new stack surface API for Windows.
[[ ThreadedRendering ]] Made linux text rendering thread safe.
[[ ThreadedRendering ]] Made Mac scrollbar and default button drawing thread safe.
[[ ThreadedRendering ]] Added core count check to determine how many simulataneous tiles to render.
[[ ThreadedRendering ]] Added accelerated rendering support to Android and Mac.
[[ ThreadedRendering ]] Implemented Windows processor core count.
[[ ThreadedRendering ]] Commented changes made.
Merge branch 'feature-threaded_rendering' of https://github.com/runrevmichael/livecode into feature-threaded_rendering

Conflicts:
	engine/src/sysw32threads.cpp
[[ ThreadedRendering ]] Add docs note for feature.
Merge branch 'develop' of https://github.com/runrev/livecode into feature-threaded_rendering
[[ ThreadedRendering ]] Attempt to make Mac background pattern drawing thread safe.
[[ ThreadedRendering ]] Added global pattern mutex.
[[ ThreadedRendering ]] Add thread-safe inc/dec functions.
[[ ThreadedRendering ]] Ensure MCPattern is ref-count thread safe.
[[ ThreadedRendering ]] Ensure MCGImage is ref-count thread safe.
Merge branch 'develop' into feature-threaded_rendering
[[ ThreadedRendering ]] Fixed build error on Windows.
Merge branch 'feature-threaded_rendering' of https://github.com/runrev/livecode into feature-threaded_rendering
Merge branch 'develop' into feature-threaded_rendering
Fix build error for Windows server.