update version to R21
admin.yell is back since R21

- remove changes from ca533a24226ca557aa2245c98ab3d7f0d9e43293
use 'teamFactionOverride' instead of teamXFactionOverride'

vars.team1FactionOverride, ..., vars.team4FactionOverride was in R19 replaced by 'vars.teamFactionOverride'
Merge pull request #164 from ozon/improvements/bf4_parser

[BF4] R21