CTMF - Constant Time Median Filtering

[HolyWu]

https://github.com/HomeOfVapourSynthEvolution/VapourSynth-CTMF

[HolyWu]

Update r3.


Add opt parameter and code path for SSE2 and AVX2.
Change the supported bit depth to 8, 10, 12, 14 and 16.


Update r4.


Add faster SIMD code for radius 2.

[HolyWu]

Update r5:

Add AVX512 optimization.
Add 32 bit float support for radius=2.