Clean up enqueuing and post-processing files (part 2).

Instead of starting a timer (with delay 0) for each album, just enqueue
all albums in `callback()`, one after each other.

If you have a *huge* number of albums, this will freeze the GUI for a
few seconds (leaving some artifacts in the tagger's window). But one
may think of this like a mutal mode -- ecxept there is no mutal
requester at them moment. If this bugs somebody, I suggest adding a
timed "Work in progress" requester and/or setting a
hourglass-mouse-pointer.
Cleanup: Rename working method.
Minor code clean-up: Rearrange code.
Bump plugin-version and plugin-api-version.
Rename the plugin, giving it a more spelling name.
Adding myself as author.
Line-wrap the plugin-description.
Add some comments.
Remove unused imports.
Mimic tagger._file_saved for the case the album will not be removed.
Change `is_well_identified()` into a method.

Need this to make the log-system available in there, to be able to remove
the print statements.
Use the log-system instead of print statements.

Just start `picard --debug` to get the output.