Adds support for Xbox and Nintendo style game controllers. The gamepad
controls are documented on the README and in the game's Settings window.
The buttons are not customizable yet, except that the player can choose
between two button styles:
* X Style (default): "A" button is on the bottom and "B" on the right.
* N Style: swaps the A/B and the X/Y buttons to use a Nintendo-style
layout instead of an Xbox-style.
* magicform is a helper package that may eventually be part of the go/ui
library, for easily creating structured form layouts.
* The Level Publisher UI is the first to utilize magicform.
Refactor how level publishing works:
* Level data now stores SaveDoodads and SaveBuiltins (bools) and when
the level editor saves the file, it will attach custom and/or builtin
doodads just before save.
* Move the menu item from the File menu to Level->Publish
* The Publisher UI just shows the checkboxes to toggle the level
settings and a convenient Save button along with descriptive text.
* Free versions get the "Register" window popping up if they click the
Save Now button from within the publisher window.
Note: free versions can still toggle the booleans on/off but their game
will not attach any new doodads on save.
* Free games which open a level w/ embedded doodads will get a pop-up
warning that the doodads aren't available.
* If they DON'T turn off the SaveDoodads option, they can still edit and
save the level and keep the existing doodads attached.
* If they UNCHECK the option and save, all attached doodads are removed
from the level.
