V2 - Jan 09, 2021 improvements

V2 - Jan 9, 2021 improvements

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* added weapon kill minimums to minimize big misses when attacking
* added an Automatic Shotgun, wasn't really a zombie game until this point.
* added a kill splash value (to support Shotgun & future weapons) so each shot can do more damage.
* added dynamic zombie counts based on player's situation
* added additional messages if player is out of ammo or low on hp
* added game-end stats
* cleaned up mobile display