CovenantMissionHelper

- improved target selection, especially "all adjacent enemies"
- fixed DoT and HoT ticks
- fixed damage value calculation with damage modifier and additional damage buffs
- fixed reflect damage value calculation
- added units with irregular attack (range type unit who attack closest enemy)
- fixed bug: completed mission's result sometimes didn't cleared
- fixed bug: buffs sometimes removed earlier when it should
- stopped spamming in chat
- fixed calculation of total rest HP in completed mission