0.0.21

8117f43 - bump version to 0.0.21 (Kalle)
a4ac50b - add isteamkill, isselfkill, player team and isteamflash and isselfflash for challenges (Kalle)
b58b960 - fix: make ranking during warmup possible (Kalle)
e00c3ae - fix: add isduringround check to challenges (Kalle)
ad0a07b - fix: show correct ranking in !stats (Kalle)
b873bb1 - fix: show names of players in challenges (Kalle)
dbe4ab9 - fix: add !stat as command (Kalle)
c74a8bb - improvement: hide challenges on death, show after respawn (Kalle)