In preparation for adding a configuration file and command-line
arguments, add code to use argparse to parse the command line. This is
at this point nonfunctional with the exception that the code now
enforces exactly the correct number of arguments on the command line
rather than silently ignoring extra arguments.

Allow the Android ID to be specified in the configuration file or on
the command line, or randomly generated and saved in the configuration
file automatically.

The code was using the storeId field in songs to import them, when it
existed. I don't know why it was doing that, but it wasn't working for
me -- songs added via storeId simply weren't appearing in my
playlists. Removing that logic and always using the id, never the
storeId, fixed this problem. This change may not be "correct", but all
I know is that the code wasn't working for me without the change and
is working with it.

When searching for a track, if there are multiple matches and some of
them are already selected, then use the ones that aren't.

When there are multiple search results, prefer exact matches rather
than substring matches for title, album, artist.