Implement support for `frame` argument for `capture()`
Implement support for `frame` argument for `capture()`

- capture(frame) supports nested frame ranges, for example
```python

frames = [1, 5, range(10, 30), [50, 60, 70]]
capture.capture(frame=frames)
```

- capture(raw_frame_numbers=False|True) added for raw frame number output for sequences in image format. This is now also used for snap() so it names the file to the exact frame being snapped.

mottosso/maya-capture,BigRoy/maya-capture,abstractfactory/maya-capture