Kvm48

This release acknowledges the fact that KVM48 is now completely broken. See 11.

This release introduces new command line and config options, in addition to improvements and bug fixes.

- New command line option `-M, --multiple-instance` allows multiple simultaneous instances of kvm48 (use with caution).

- New command line option `--dump-config-template` dumps the latest configuration file template.

- New configuration option `convert_non_bmp_chars` to enable replacement or removal of non-BMP characters (code points above `U+FFFF`, e.g. most emojis) in filenames for compatibility with legacy filesystems with only UCS-2 support, e.g., FAT32.

- List of successfully downloaded files is now printed at the end of each session.

- The `names` config option is no longer required when running in perf mode.

This release does not contain new features or break compatibility in any way.

- [caterpillar](https://github.com/zmwangx/caterpillar) is now automatically installed as a dependency through pip.

- Improve onboarding experience.

- Issue warnings when performance VODs returned are 720p instead of 1080p (see 7). This has been the norm since early November, and there's nothing to be done on the client side, but it's probably a good idea to alert users to the fact and inform them that the client has tried its best.

- Include more info about the execution environment when --debug is on.

- Link to issue reporting guidelines when the program halts due to non-recoverable exceptions.

Breaking changes:

- Windows config and data dir changed from LocalAppData to AppData (that is, Local vs Roaming). Manual migration required.

Other changes:

- m3u8 downloads now require [caterpillar v1.0](https://pypi.org/project/caterpillar-hls/1.0/) (up from v1.0b1).

- Introduce perf mode: https://github.com/SNH48Live/KVM48perf-mode.

- Parts of the download workflow have been restructured for the better, and aria2 and caterpillar download commands are both retried up to twice (for a total of up to three attempts) in the case of failures.
- New `--edit` option to open the config file in a text editor.
- New short option `-n` for `--dry`.
- Drop official support for Python 3.5 (though code is still compatible at the moment).