LICE: check for non-negative non-zero dimensions before trying to malloc -- from bb7bb2b6
SWELL: fixed InvalidateRect prototype -- from 670ec18f
SWELL: fix for SetMenuItemInfo() with MIIM_SUBMENU, it previously released submenus
WDL_SharedMutex::SharedToExclusive() and WDL_SharedMutex::ExclusivetoShared() -- untested -- from 2461978b
LICE_palette: added LICE_BuildOctreeForAlpha() and LICE_BuildOctreeForDiff(), small optimizations throughout -- from 81779e14
LICE_gif_write: optimized writing for various alpha cases, improved auto-transparency to ignore alpha channel and also only regenerate palette for changed pixels -- from 9a9b69cf