Removed dependency on cairo-xlib, glib

Now we only depend on cairo and optionally SDL2.
Added png surface saving, proper DNA format is TODO
It compiles now

The CUDA code spits out junk, but I'm pretty sure that's my fault and I
forgot some declarations it depends on.
CUDA works now

I'm not seeing a difference in performance. ennui overload
timelapse
changeball, see below the fold

* added signal handling: now hitting ctrl-c (SIGINT) will still save your
  files.

* name and memory management cleanup. valgrind is still mad at me but
  the calls are there.

* a new README, it talks about things in the makefile that aren't
  actually there yet, sorry~
Merge branch 'nv'

Conflicts:
	README
	mona.c
Merge branch 'master' of https://github.com/Alloyed/mona

Conflicts:
	Makefile
	mona.c

Added WITH_CUDA make variable.
Fixed build with WITH_SDL=off and WITH_CUDA=off