* Renamed 'svtplay-dl' to 'svtplay_dl.py' which conforms with the Python
guidelines and can be imported from other scripts (names with '-' cannot).
* Created the wrapper 'svtplay-dl' for backward compatability.
* Broke out the major parts of main() into get_media()
* New Options class corresponding to the command line parameters.
* Modified how the log used and progress information written so they can be
easily configured by the caller.
