Planned Breaking changes for version 2.0.0

[devsnd]

This is a record of planned breaking changes for a major version change

• The track and track_total field should return integers instead of
• The disc and disc_total fields should return integers instead of strings
• Mark TinyTag subclasses as private
• Mark audio_offset field as private
• TinyTagException should not inherit LookupError
• Dropping python 2.7 support
  e.g. usage of unicode https://github.com/devsnd/tinytag/blob/master/tinytag/tinytag.py#L211
  float() casting https://github.com/devsnd/tinytag/blob/master/tinytag/tinytag.py#L336
  use bytes.decode instead of codecs https://github.com/devsnd/tinytag/blob/master/tinytag/tinytag.py#L631

[devsnd]

Question from mathiascode: Should we keep exposing MP3, OGG etc interfaces directly, or only the TinyTag interface in the 2.0 release?

[mathiascode]

@devsnd I think we should mark the audio_offset variable as private. It's not available/used in several of our formats, and not very useful as-is without an additional variable like audio_size.

[mathiascode]

Useful tool for upgrading syntax: https://github.com/asottile/pyupgrade

I'll create a new branch for 2.0.0 soon, which can eventually be merged into master. I see there are some previous branches that we could use as a starting point.