Fix a string underflow.
Merge remote-tracking branch 'origin/master' into project-restructure

Conflicts:
	src/ui_sdl.c
Add define statement for VM_H
Cleanup of vm.h and vm_slow.c, no more warnings
Fix warnings in compiler.c
Cleanup of ui_sdl.c, no more warnings
Standardize Makefile flags across supported systems, enable -Werror