Tray's chemical procession is made into a separate proc.
Nutriments again affect plant's mutations and yeild.
Containers will no longer splash their contents at trays and biogenerators (fixes #2992).
Almost all spawn() removed from grown creation.
Minor fix
Small fix
Conflict fix
Nutriment class
Potency and chemicals fix
Merge pull request #3189 from Kelenius/master

Hydroponics fixes, #2992, #3002, chemicals, attackby()