UI improvements specifically for mobile (running the game with the
`-w mobile` or `-w landscape` options) screen sizes.
* Rework the Settings window to be mobile friendly to landscape
oriented screens (`doodle -w landscape`) and migrate Options tab
to magicform.
* The toolbar in the Editor will be a single column of buttons
on small screens, such as `-w mobile` (375x812) portrait mode
smartphone. On larger screens the toolbar shows in two columns
of buttons.
* Fix tooltips not drawing on top.
* Centralize the hard-coded references to specific font filenames
* Add cheat code: `test load screen` to bring a sample loading screen up
for a few seconds. It needs improvement on `-w landscape`
* Load SDL2 fonts from go-bindata storage so we don't have to ship
external font files on disk.
* Dedupe names of doodads so we don't show double on the front-end
(go-bindata bundled doodads + those on local filesystem)
* Use go-bindata for accessing wallpaper images.
* Better flashed messages walking you through the Link Tool.
* Stylize the title screen (MainScene) by rendering a live example level
as the background wallpaper, with mobile doodads in motion.
