Tank Def 2.0

Changelog:

- Added full map vision for Players 3,4,5
- removed starting zealots to ensure balance testing
- added choosable difficulties for 2 and 4 players (thanks to spinecrawler D! maker, i used your trigger for that :>)
(2 players = 1 zealot every 20 kills, 4 players = 1 zealot every 10 kills)
- changed some stats of the first 6 waves to make them harder.

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