19.02

New Features:

• Added full support for mastering voice effect chains
• Added optimized paths for 1->8 and 2->8 channel mixing

Fixes:

• Build system no longer requires SDL2 CMake config files
  • If desired, set SDL2_LIBRARIES and SDL2_INCLUDE_DIRS manually
• Fix submixes being silent when the update size doesn't align to the input channel count
• Fix effect processing for sources that don't fill a whole update's worth of samples
• Various MaxFrameCount/ValidFrameCount accuracy fixes
• Various off-by-one fixes for resampling