As was promised, in this update Build mode was added. Now you can create your own levels, share them with other players and try other's creations.
For saving your level, in build mode you have to press left button on the top of the screen, so level's textcode is generated.
To load your level, put this textcode in the input box and press right button on the top of the screen.
To start level press Play. After finishing the level you will be returned to editor.