Specfile

- specfile now once again supports EPEL 8 and Python 3.6. (256)

- Fixed infinite loop when removing macros with `%` in the name. (244)
- Added a possibility to undefine system macros by setting a macro value to `None` in the `macros` argument of the `Specfile` constructor. (244)
- Fixed a bug in processing options of `%prep` macros. For instance, when a quoted string appeared inside an expression expansion, it could lead to improper parsing, rendering the spec file invalid after accessing the options. (253)

- Parsing has been optimized so that even spec files with hundreds of thousands of lines can be processed in reasonable time. (240)

- Specfile library now handles multiple `%changelog` sections. (230)

- Added a new `guess_packager()` function that uses similar heuristics as `rpmdev-packager`, meaning that the `Specfile.add_changelog_entry()` method no longer requires `rpmdev-packager` to guess the changelog entry author. (220)
- The `Specfile.add_changelog_entry()` method now uses dates based on UTC instead of the local timezone. (223)

- Added `Specfile.has_autorelease` property to detect if a spec file uses the `%autorelease` macro. (221)