0.3.0 — New Accidental API

What's Changed

• chore: bump versions as of Dart SDK 2.19 by @albertms10 in #7
• refactor(accidental): rewrite new Accidental class by @albertms10 in #8
• docs: reference new Accidental class instead of enum by @albertms10 in #9
• refactor: make Accidental.natural default by @albertms10 in #10
• refactor(enharmonic): rewrite based on semitones by @albertms10 in #11
• refactor(notes): rename notes using the English convention by @albertms10 in #12
• refactor(accidental): rename value → semitones by @albertms10 in #13
• refactor(note): add static const constructors by @albertms10 in #14
• refactor(src): reorganize directories by content by @albertms10 in #15
• refactor: rewrite enum members by @albertms10 in #16
• refactor(relative_tonalities): remove class by @albertms10 in #17
• refactor(int_mod_extension): rewrite mod functions into extension methods by @albertms10 in #18
• refactor(note): move fifths distance functions to class methods by @albertms10 in #19
• perf(tests): run tests from index main.dart file by @albertms10 in #20
• chore(pubspec): bump version 0.3.0 by @albertms10 in #21

Full Changelog: v0.2.0...v0.3.0