1/16-pel motion vector storage

Motion vecotrs are always stored with 1/16-pel precision and the High
precision motion vector SPS flags are removed.

The following strategies are followed:

1. Motion vector data in the buffer are always stored in high precision.
2. Motion vector used for motion compensation are always in high
precision.
3. Motion vector difference data are always in low precision.
4. Encoder side motion estimation always use low precision.
5. Motion vector bits calculation are always performed in low precision.
6. Candidates of motion vector prediction list are always in low
precision.
Status Job ID Name Coverage
  External
passed jenkins