Disableable E-Tanks Improved UI

[aquanight]

New and improved disableable E-Tanks UI.

• Move up into the e-tanks with D-Pad Up from the "top" of either menu. Current e-tank is hilighted with a flashing green similar to the "auto-cancel ammo" icon.
• Select any empty e-tank and press A to toggle it. Disabling a tank disables all tanks "above" it. Enabling a tank enables all tanks "below" it.
• Default tank selection is "first empty tank" if any, otherwise "last disabled tank". It's one quick "Up then A" to enable/disable all tanks (of course if you collect one in the process).

Things to still do:

• Try to get a proper selector sprite up in the HUD.
• A few extra hooks in the other equipment category button responses to avoid same-frame button press bugs.