Fix rounding error [PART.1] Round half up when compositing body coverage and body alpha
Fix rounding error [PART.2] Round half up when compositing border coverage and border alpha
Fix rounding error [PART.3] Round half up when compositing body coverage and body alpha and alpha mask
Fix rounding error [PART.4] Round half up when compositing border coverage and border alpha and alpha mask
Enabled addition draw routine with \k family
Refactor. Use template function to save some copy/parse code.
SSE2 optimization of addition draw routine[PART.1]
SSE2 optimization of addition draw routine[PART.2]