cleanup SIZE_NONE. empty CU has MODE_NONE.
analysis: Dump best MV statistics and re-use this for analysis load mode

This patch fixes a bug in inter slices in analysis=load|save mode. Inter data
for all partitions is now saved correctly.
x265: remove redundant variables from intra and inter analysis structure
param: add default value to analysis mode
x265: create and initialise recon object if analysis mode is enabled
api: replace analysis data with pre defined constant
api: cleanup
x265: more meaningful error messages in analysis