v0.0.4-alpha: return buses, expanded automation, grid sizes, clip management

What's Changed

• Berlin theme: distinct muted track colors by @alexanderwanyoike in #45
• feat: complete arrangement clip management by @alexanderwanyoike in #47
• Busses: Ableton-style return channels with per-track sends by @alexanderwanyoike in #46
• Editors: musical grid sizes, triplets, snap and adaptive mode by @alexanderwanyoike in #48
• Release: return buses, expanded automation, grid sizes, clip management (v0.0.4-alpha) by @alexanderwanyoike in #49

Full Changelog: v0.0.3-alpha...v0.0.4-alpha