Synthmeat, Synthbutt, Synthbrain, cash seeds working.

![14h67p5](https://cloud.githubusercontent.com/assets/4081722/3295562/eba83236-f5c3-11e3-9cde-6cf4642f34e5.png)
Thanks to the goons for permission to use the sprites.

Adds Synthmeat, Synthbutt, and Synthbrains to Botany.

Fixes being unable to make cash seeds from cash trees.