started working on zoom functionality
used jensens advice... again!
+ quickfasthotfix (fixed a few bugs with the zoom feature)
ignored the stderr.txt and stdout.txt files.
Fixed the stupid gravity bugs. + Escape Key quits the game
I spent a few hours figuring out that I had to reverse the order of the i and j variables in the two outer for() loops of the gravity checking mechanism. I was column by column. That was a VERY VERY BAD IDEA. I changed it to checking row by row.
Merge branch 'zoom' into gravityhotfix2
Now the gravityhotfix is merged with the zoom feature. I will be merging this into master and pushing.

Conflicts:
	NatureSim/cell_engine.h
	NatureSim/main.c
	NatureSim/materials_and_cells.h