Changed hydro trays, fertilizer and syringes over to use the reagent procs.
Reapplying some fixes that I think DM may have saved over, whoops.
Adjusted process_reagents() so hydro trays are refillable with water and nurients when the tray is dead/empty.
Adjusted gas exude code.
Merge pull request #5834 from Zuhayr/hydroponics

Changes dev hydro to use reagent procs.