Variable RW and parfor break
-Variable lookup now utilizes a proper read/write lock
-parfor loops now support break statements to stop all other threads
	-continue has technically always been supported
-Added test cases for the above scenarios

NOTE: error condition noted a couple commits ago has been tested further
	-cause still unknown, but seems to only occur when using parfor loops inside a parfor loop
Merge branch 'master' of github.com:IanFinlayson/tetra