Rewrite Limiter asm, remove SoftWire dependency.
Rewrite SwapUV YUY2 asm
Rewrite VerticalReduceBy2 asm
Disable SwapUV and HorizontalReduceBy2 asm for small clips
Remove TemporalSoften mode 1.

Keep the parameter for compatibility with older scripts.
Also remove isse version of accumulate_line for mode 2. The only difference was quite useless prefetch instruction.
Rewrite TemporalSoften asm
Enable TemporalSoften on x64
add sse2 intrinsic version of Overlay Blend mode
remove leftover debugging code (sorry)
Simplify Limiter SSE2 path.

Also fix compilation in 64bit mode.
change MMerge_SSE to use por instead of pxor
remove auto type as it's only support in newer version of msvc
Replace uc define with BYTE for consistency in Blur
Clean up Blur code a bit

Remove mmx parameter
add sse2 intrinsic version of Overlay lighten/darken mode
Rewrite vertical blur/sharpen asm
change unsigned char type to BYTE
rename blend_asm.cpp/h to blend_common.cpp/h
fix compile error cause by file moving
restructuring masked_blend function