- fix zero=false case for shape helper function (mt_rectangle, mt_circle, mt_diamond etc...)
- lut expressions: report obvious script error (unbalanced stack, invalid keyword or variable, etc)
- mt_lut: reuse LUTs across planes if they are the same like in e.g. mt_lutxyz.
- 1D LUT expressions: occupy only the necessary size for 10-14 bit LUT tables (was: buffer was always reserved for 16 bit data)
- mt_merge: error is luma=false, mask is greyscale but clip is not greyscale
- mt_merge new parameter hint for chroma placement when luma=true and 4:2:0: "topleft"
"topleft" is a new option for 4:2:0 videos only
- Source syntax update for GCC (20201229)
- CMake build environment, builds on Linux,