Layering, zoom-factor, deleteable edge tiles.

There have been a lot of smaller updates in the last time that have not been loudly proclaimed, so i thought i will sum them all up in a devlog :)

PP now has different layers, where objects are drawn on.

One advantage of it, that it boosts the performance, as static objects only need to be drawn once, and not updated on every frame

The advantage from a user perspective is, that now there is also a foreground layer, with 2 new objects. One objects can hide and reveal a hidden area. The other will just stay in the foreground forever

One feature that has been in the tool for a while, might be useful for games that have exploreable worlds. It's now possible to delete the edge-tiles and change the transition between levels in the color selection, to create a more seamless transition between rooms.

Another feature to add more visual variety as the possibility of changing the zoom factor for the levels. It can either be adapted manually, or it will also adapt automatically, if you make your level size smaller than the default size, creating a more old-school resolution.

Some other small things that have been changed:

- a new rotating fireball object 

- the cannons now have an attribute that enables/disables cannonball collision with walls. that way you could create escape sequences f.e.

- some visual improvements, like sfx-trails for cannonballs and a popping animation for the dialogue window