- to make it clear what the functions actually do:
ndarray_to_pil() and pil_to_ndarray()
- as per code review feedback
- updated tests to use the new function names
- incoming change to pil_plugin assumed PIL Image
objects will always be from files; this is
not always true anymore. Now pil_plugin
checks to see if the Image came from a file
before trying to close its associated file.