Perform targeting in MenuActionBar::checkAction()

This allows us to use a different target depending on how we trigger the
power. If we trigger a power by clicking on its icon or by pressing
ACTIONBAR_USE, the target will be in front of where the player is facing
(at melee range). Otherwise, we simply use the mouse cursor's position.

This is a partial solution to #1168
Don't use press/hold to simulate MAIN2; Use only MAIN1 instead

This makes it so that actionbar powers are triggered immediately when
pressed with touchscreen controls. This is more appropriate for how
action RPGs are played. There are a few downsides though:

- Can't rearrange/remove actionbar icons once they're placed. They can
still be overwritten by dragging in new powers/items from other menus.
- Items can't be activated directly from the players inventory.
Consumables should be dragged to the actionbar and used that way.

In the process, I removed a lot of the __ANDROID__ ifdefs, since there
are non-Android devices that use touch controls (laptops with
touchscreens come to mind). Also, having lots of ifdefs is just plain
ugly. I'd like to keep their usage to a minimum.