Monkey Fusion

Monkey Fusion is a non-tower placeable item, alongside Road Spikes and Explosive Pineapple. Monkey Fusion will combine all towers' upgrades together.

There are some rules to Monkey Fusion that determine how it works:
 * 1) The cost is not preset. It will cost 80% of the affected towers' total cost, and will not refund the towers.
 * 2) Monkey Fusion has a range of effect. All towers in that range must be the towers you intend to fuse, and must be descendants of the same 0/0/0 tower.
 * 3) The final product will have the highest upgrade of all the monkeys in each lane. For example, 5/2/2 + 2/3/2 + 0/0/4 = 5/3/4.
 * 4) The position of the new tower will be where the Monkey Fusion item was placed. Thus, it cannot be placed on water or tracks. (This will result in some funky business like Shipwrecked Buccaneers or Monkey Subs, but we'll ignore them. They will be solved by rule 5.)
 * 5) There is a preset texture for each tower, meaning even if you're fusing two 0/0/0 it will have a new look. Just for the laziness of me, fused Buccaneers will appear slightly splintered as they go on land, and Monkey Subs will be slightly tilted and mossy.
 * 6) All effects and by towers (even before fusing) will have one of three statuses: main, ability and extra. (These will not be seen by the player, but will be in the code.) Any tower will always have one main effect, and may encounter abilities and extras along the way as they upgrade. For example, a 0/0/0 wizard already has a main attack. Intense Magic upgrades the main, Fireball is an extra and Guided Magic is an ability which affects the behaviour of both the main and the extra. Special abilities, ironically, count as extras. Mains always fuse, extras always coexist, and abilities will... well, it's hard to explain but it's kind of obvious what happens.