Enabled action icon for magboots
Removed the now-redundant verb

Less clutter for the object panel.
Prevent vox boots from enabling in player's hand

Vox players can't "dig their claws into the flooring" when holding the
boots in their hand. When enabled, the boots can't be taken off until
disabled.
Clean up check for item being equipped

Moved some common code to item.dm. Someone should probably take a look
at get_equipped_items() in inventory.dm sometime in the future.
Merge pull request #4753 from mwerezak/magboots-action-icon

Magboots action icon