Add fun elements!

[svader0]

I've got a few ideas for elements that I stole from other sites or cellular automata.
When we decide to implement a new element, create a separate issue for it so we can keep track of what we've done.

Vines: each starter vine pixel creates a random downward line of pixels 1-5 pixels in length. (See DAN-BALL Powder Game)
Fire: A gas that just sends up pixels quicky in random directions and dies off after a few frames. Changes color on the way up? (Idk how this would be implemented)
Maze: This one is kind of stupid, but we could literally just use this to have an element that just grows a gigantic maze when you click a spot.
Metal: Corrodes (changes color and slowly decays) when water touches it.
Acid: Eats through stuff depending on each material's density. This would have to be some sort of property of each element.
ANT: See DAN-BALL Powder Game. This is probably just another implementation of this cellular automata.

Feel free to add other ideas here. A lot of these depend on restructuring how our elements are represented (AKA they can't be enums anymore probably.)

[svader0]

Oh, and obviously the basic ones too. Stone, Sand. Maybe after we add fire we can have an oil element that lights on fire? We'd need each oil particle to have an isOnFire boolean, so that we can spread the fire. That's why we need to change our element representation.