18.03

New Features:

• FNAPlatform: Add GetBaseDirectory function for upcoming platform support
• SpriteBatch: Reorganize variables to make SpriteBatch.cs easier to re-use outside of FNA

Fixes:

• Effect: Allocate state changes struct as AllocHGlobal memory, fixes crash on Apply
• Video: Add width/height information to XNB mismatch error message
• SoundEffect: Fix FromStream loading for MSADPCM wav data
• SoundEffectInstance: Allow using Apply3D(AudioListener[]) with one listener
• SDL2_FNAPlatform: Fix event filter for Windows SDL_WINDOWEVENT_EXPOSED events
• FNA.Core: Fix building in the same directory as FNA