Add a config for isort (https://github.com/timothycrosley/isort)
Run isort -rc . and make import style consistent across files
Add a note about `isort` in CONTRIBUTING.md
PEP 394 makes it clear that python should only be used for applications that can
be run with both Python 2 and Python 3, python3 should be used for Python 3.
pip3 is used because that's what Python 3 compatible pip is called on at least
Arch, Debian, Fedora and Ubuntu.
Replaces the "picard-submit" icon with the icon used by the
acoustid-fingerprinter project. The "picard-submit" icon resembles the
old MusicBrainz brain logo, but the submit button doesn't actually
submit anything to MusicBrainz since the switch from using PUIDs to
using AcoustID, but instead submits to the AcoustID.org server. A lot of
people are already confused by this, so making it visually a bit less
connected to MusicBrainz might help this confusion, however slightly.
`acoustid-fingerprinter.svg` was copied directly from
632e87969c/images/
and then converted to a 22×22 PNG using Inkscape and run through
`optipng` and `advpng` as per commit d26c908587.
The acoustid-fingerprinter icon was made by Lukáš Lalinský and is
available under the GPL2 license, the same as MusicBrainz Picard:
632e87969c/COPYING.txt
Some noticeable points:
* `save_state` can check whether table is loaded or not. No need to
check it in `accept` and `reject`. Also `table_loaded` isn't required
anymore.
* Keep file formats list in alphabatic order, in `makeqrc.py`.
* Import `Track` and use `isinstance` to check whether object belongs to
it.
16x16, 24x24, and 32x32 are based on Picard_logo_icon.svg.
48x48 is based on Picard_logo_small_no_text.svg.
128x128 and 256x256 are based on Picard_logo_no_text.svg.
All PNGs were processed with `pngcrush -brute -reduce` afterwards, for
reduced filesize.
python setup.py build_ui wasn't very explicit when run without installed pyrcc4,
messages are now better.
Use distutils.spawn instead of subprocess.call
When an error occurs during loading of a release, it will be visible
in info dialog for this release (which was unused).
New icon was added to mark visually releases with errors, and scrollbars
will appear in info dialog if needed.
