Added flying enemies and player animations

I have added a number of different enemy types, including some flying enemies, I think this will likely be most of the enemy types that are in the final product.

I have also added some animations to the player for when you start and end the round.

I may or may not have turned up the number of enemies to make the screenshots look more interesting but hey, once I implement the upgrade shop, one of the items which I am intending for the player to buy is upgrades to the number of enemies that appear, so it's more like I cheated in game than cheated on the screenshots, and it's my game so I'm allowed.

Something which I have found surprising is the extent to which I am having to override the default physics and collision system in Unity to make the game 'feel' nice, I know that a Yeti flying through the air and stomping on robots is not exactly realistic, but I was thinking I'd just lower the gravity here... increase the bounciness there.. and done! 

This has not been the case, I am having to directly control a large part of the player movement and interaction with the enemies, and I think this will only increase as the development progresses.