added missing include
updated .gitignore
replaced sdl types with clunk ones
started process of removing sdl
added debug compiler options
implemented load(wav) in sdl backend
removed sdl includes, replaced sdl_mix_maxvolume with MixMaxVolume const
fixed documentation
added AudioFormat struct
added template mixer implementation
added resample stub
added missing context initialization
removed Context::convert
implement mixing via shifting
implemented resampling
throw exceptions on invalid formats
added start/stop methods to sdl backend
fixed overflow in mixer routine