fixed some bugs with the Rock Shower ability and ClusterShower backing script. Clusters should now do damage and the amount of rocks that can be spawned from an upgraded ability is capped by the cooldown of ClusterShower (per target). Kind of, it's a bit weird.
Igniting Blast didn't have its improvements linked
improvements now persist if the ability is reset due to upgrading/upgrade removal
made an attempt to make the cluster spray from ClusterShower used to upgrade projectiles/blasts spray normal to the collision point (without using Collision2D)
made blasts rotate to face the direction of collision when being created by a projectile collision
fixed bug where you couldn't set a new active ability over an upgraded ability
did some reorganising moved where the blast scripts go
made a base poolable object class
enemies now drop XP and you can only improve an ability if you have enough XP