Visual debugging

Hi,

Lately, I've been still working on several little things:

I Merged the sprite position and offset into one float, both in scripting and in the inner API.
I left proper pixel perfect rounding where necessary, to keep avoiding the flipping seen because of the map mode view point and technique chosen.

Based on that, I'll be aiming at using float based path coords for path move events and collision detection which should all in all simplify a bit everything.
To start with something helping, at least IMO, I added a debug view in the map mode showing the different collision types in a visual way:

The blocking area can be displayed for debugging purpose.

I also removed the fringe layer support in both the game and the editor, and made other minor fixes.
I guess that pathfinding apart, the engine is quite in a good shape to go further in the story now. :)