Further Hydro Cleanup

Fixes #3880 : Mapped or Adminspawned Growns will take on the default variables of their seed type.
Fixes #3828 : Meteor Pen projectiles are now visible

Some more refactoring, clearing up the growninedible.dm. Deletes hydroitemcode.dm. Keep code with the definitions, ew ew.
Merge pull request #4105 from Cheridan/bugslaying

Further Hydro Cleanup