Small optim

Now SDL only redraws the part of the screen that needs it.
Update optim: now correct (CLR & overflow)
Better system management

Now can be paused from the start
Uses a thread to leave the main thread alone
better use of the SDL events
better code structure for when we'll go into actual compiling
Merge branch 'master' into llvm

Conflicts:
	Makefile
	ch8vm.c
	ch8vm.h
Merge from emscripten: use a memory array for loading memory

Instead of whole ch8state, easier for manual modification through llvm
simple refactoring

The opcode don't use the global variables anymore
First working version with manual opcode call
Cleaned up prototype with manual parsing

Still have to work out jumps and routines