Set version number to v0.21.1 for release
Fixed problem of first arena run not being detected

Previously starting a new arena run would not be detected for the first match, because the log regex was incorrect and thus not used.
Adjusted pixel detection for play screen

The screen has become darker in the last patch, adjusted detection accordingly.
Merge branch 'master' of https://github.com/HearthStats/HearthStats.net-Uploader
Merge branch 'master' into opponent-overlay
typo
should handle cards discarded by soulfire/doomguard in opponent