Added Coro yield
Added (untested) Win32 Coro implementation
Fixed Coro implementation for win32
Removed unnecessary need for coros not to terminate dating back to Steve Dekorte's implementation when a ucontext link is not established
Windows Coros now correctly yield to their parent after execution is complete
Now that coros can terminate, startCoro should not free them. Instead, they must be freed manually when they end
Merge pull request #834 from shamanas/master

Win32 Coro implementation + yield method