LIGHTING ENGINE, Logging system, fix to a vertex shader bug and micro optimisation + better code

[Jukitsu]

use items(), values() for dictionaries, fixed a weird const keyword hanging out in the vert.glsl and added logging.

[Jukitsu]

Did github just whine about a small variable name change ??

[obiwac]

Merged, will apply for chunk_position, render_chunk in self.chunks.items(): to other episodes at a later date.