WIP: remove deprecated IMV mode SPS parameter
AMVR (formely IMV) now has only one mode, which used to be mode "2"
- remove SPS imv_mode parameter
- remove encoder configuration for mode "1" (mode "2" replaces mode "1")
- adapt config files to refer to mode "1"
- rename SPS syntax elements and access functions to AMVR
Note: IMV to AMVR renaming in other parts of the software should be done by proponents.
To be merged after !279 (merged) and pending testing.
Edited by Karsten Suehring