Updates: automation, midi learn and drum samples

• Automation lane per pattern (steps or smooth) for volume, pan, reverb, delay, master and filter
• Song automation lane in the playlist
• MIDI learn: map knobs and faders to any automation target
• Drum sounds panel: load your own sample into any drum, edit the velocity of every hit
• Drum kits (Retro, 80s, Acoustic) and euclidean rhythms
• Six more presets (Rock, Techno, Funk, Trap, Bossa nova, Reggae)
• store.js: samples are kept in IndexedDB and saved inside the song file