Swift backend sets current working directory to /

[petercorke]

Running this simple example

>>> from roboticstoolbox.backends.Swift import Swift
>>> backend = Swift()
>>> backend.launch()  # create graphical world
>>> backend.add(panda) # add robot to the world
>>> panda.q = panda.qr        # update the robot
>>> backend.step()    # display the world

changes the cwd. Not sure which command does this.

A problem if working in ipython and repeatedly using %run to test an example script.

[jhavl]

Fixed on future branch