With all trackers.txt trackers being included in generated .torrents,
we can now be certain the magnet (which use trackers.txt) and the .torrent
uses will not be split up in different swarms in case the main announce dies.
(That is, if uploaders add enough of their own trackers and additional trackers
were deemed unnecessary (at least 5 already), the magnet and .torrent would only
share the main site announce)
* Replace all `from nyaa import app` imports with `app = flask.current_app` (or `from flask import current_app as app` where possible)
* Add a separate config object for top-level and class statements as `nyaa.extensions.config`
Required because those codes don't have app context at the time of evaluation/execution.
* Remove `routes.py` file and register all blueprints in `nyaa/__init__.py`
* Refactor `nyaa/__init__.py` into an app factory
* Update tools
* Update tests (temporary, will be replaced)
* Update isort settings
* Apply import sorting (isort) on all files in nyaa/
* Fixed Flake8 errors in nyaa/ (see PR for list)
* Add isort to lint.sh and requirements.txt