Goodies

[LucasThompson]

This merge contains a number of efforts:

• A major refactoring of waveform.component.ts
• An improvement to the feature extraction menu
• A fallback for browsers without MediaRecorder (not perfect, still needs some work)
• Undo / redo
• Export recordings
• Remove cards
• Some work towards session loading, but there is still a feature branch with additional changes which haven't been included here
• Various small bug fixes which I can't remember