A little more balance

• Now, to create iron screws, you also need plasma cells.
• Changed the amount of required resources of the 7th stage.
• Fixed a bug when a grown plant required watering.

There is a bug that is related to the harvesters - sometimes they stop being selected by the mouse, so far I can not fix this bug because I can not understand the steps to reproduce it ..) if anyone knows them - write under this note :P