Bunch of Bug-Fixes and Improvements

This time I concentrated on bug fixes and general improvements, so there is only one new level. 

This level is a rather easy one, introducing the concept of using frames of different size to change the size of other frames. The purpose of this level is to introduce that concept slower, thus flatten the difficulty curve.

Frame is improved with this update in the following ways:

• The levels "Rinse And Repeat", "Stairway", "Green" and "Through And Through" had alternative solutions that were easier than the intended solution. So these levels are changed to avoid cheese. 
• Some playtesters complained that the walking speed feels to slow, so it is notably increased, now. Though increasing the walking speed itself was just a question of changing one number, this change actually took some time since it implied revisiting all levels and making sure that gaps the player is not supposed to jump over can indeed still not be jumped over.
• A small coyote-time of a few frames was added. This makes the jump more reliable in situations where there is only loose ground contact.
• The store-page was slightly redesigned.
• The cookie in the "Cookie" scene fades in and out during level transitions, now. 
• The transition glow<->non-glow is now animated for spheres and buttons. 
• The opening animation of frames can now be interrupted/aborted. This is especially usefull in the case where the opening of a frame is stalled because it is inside another frame. In that situation the status of the frame can now still be changed.
• In two levels the position of a moving frame was not interpolated each render frame, resulting in slightly jittery movement.

And here is the list of bugs that are fixed, now:

• In some situations the symbols on moving platforms were clipped incorrectly, meaning that they disappeared for a few frames.
• In some situations frames were rendered with glow, although the glow was removed. 
• The speed of frames was not initialized correctly, when opening a frame. This resulted in a flickering for one frame when a frame was opened. 
• The rift-open-animation did not scale correctly, when that frame was inside another size-changing frame. 
• In a very specific situation the opening animation of a rift could suddenly change its appearance. 
• The character still walked even when the menu was open.