Replaces 2-dimensional arrays for storing reference samples in
intra prediction with two 1-dimensional arrays. This reduces memory
usage for these buffers from 792KB to 6KB.

Simplify code and rename variables to conform to guidelines.
Code simplification should result in fewer calls to
CodingStructure::getCURestricted().

Don't reallocate buffers if already allocated
Initialize pointers to nullptr

- refactoring of MatrixIntraPrediction.h/.cpp (merged classes MatrixIntraPrediction and PredictorMIP, removed namespace Mip)
- removed unused variable posBias in function computeReducedPred
- fixed list size in function reduceHadCandList

Move DPDC code for HOR/VER to xPredIntraAng function to be
consistent with other angular modes. This also avoids code
duplication by having the same PDPC code for HOR and VER modes.

Clipping is not required for the DC/Planar PDPC process since
the result is always within the valid range

Remove fields whRatio and hwRatio from the IntraPredParam
structure when JVET_O0364_PADDING is enabled as they may be needed
only once. When ratios are needed use logs, adds, and shifts
instead of divisions and multiplications.

Add initializer for angularScale when JVET_O0364_PDPC_ANGULAR is
enabled

Make life easier for the auto-vectorizer.
2% runtime decrease for AI in limited tests

1. indentation
2. function naming
3. Class declaration positions

initial commit of JVET_O0119_BASE_PALETTE_444: palette in HEVC and palette mode coding in JVET-N0258