New hero! And some balances and QoL improvements. — HellEscape Steam update #814177

- Added 'Summoner' hero. - Made 'Blizzard' spell stronger. - Added cold resistance to 'Fire Shield' and increased flames distance per level. - Added 1.25 seconds delay before collision detection begins on new spawns, to prevent annoying push-back from ballista and other summons and immediate death of minions. - Added health bar to some special enemies, like gates. - Made poison darts less effective against special enemies. - Added 'Summon Mastery' skill. - Removed 'Summon' tag from Wasps since it's a projectile anyway and its not affected by summon bonuses.