added 2 new commands:

- /itemeditor potioncolor <red amount 0-255> <green amount 0-255> <blue amount 0-255>

allows to select color of the potion mixing the colors, to choose your color you may use this google page

- /itemeditor potioneffect add <effect> <duration seconds> <level 1+>
- /itemeditor potioneffect clear

add an effect to the potion with choosen intensity and duration
you may also clear the potion effect you added

added examples on plugin page