WPF: More refactoring of WaveFormCacheService/WaveFormRenderingService. Fixed several bugs in rendering partial wave forms; the wave form tiles are now generated correctly (only at 100% zoom for now). WaveFormControl no longer uses WaveFormRendererService; it only uses WaveFormCacheService. This means the UI no longer requests new bitmaps depending on control size change; the new bitmap tiles are generated when necessary in the draw methods (WaveFormCacheService is async).