Updated version in pom.xml to 0.5.1 for next dev build
Added locking player inventory slots using permissions to use as menus
Modified /menu grab command to first attempt to place items into the same position in a player's inventory as they are in the menu
Fixed NPE in MenuGrabCommand
Allow /menu grab of armour from menu from row 5, in the order: boots, leggings, trousers, helmet
Check that the armour slots are really armour before adding them
Prevent players from dropping items out of locked slots using the drop key
Updated version in pom.xml to 0.5.2 for next development build