Do proper leftover calculations when adding equipment to slots

ItemStorage's add() function will try to fill up all slots in the
storage area. This isn't what we want for equipment. Instead, any
overflow should be added to the player's regular inventory.

In MenuInventory:activate(), I simplified searching for valid slots.
It's now a single loop instead of two separate loops.
Merge pull request #1166 from dorkster/fixes

InputState: Fix build by using fabs() instead of abs()
Merge pull request #1167 from dorkster/menus

Do proper leftover calculations when adding equipment to slots
Android: disable keyboard. Drag items by one.
Fullscreen mode on Android
Attempt to fix MAIN2 item/power activation for Android
Merge remote-tracking branch 'remotes/dorkster/input'
avoid continuous usage of touch-and-hold to avoid wasting of e.g. potions
Merge pull request #1170 from igorko/master

Android fixes
Suppress tilewidth and tileheight messages when loading maps

I was orginally going to change the Tiled Flare plugin to remove these
values from the export process. While these properties are not used by
the engine, they *are* used when importing maps to Tiled.