State: Make inputLinks, linkableActions, scenes and macros into nodes

[funwithtriangles]

This may simplify areas of the app such as displaying input links / linkable actions / params in panels without having to specify which type they are and therefore having to know where to look in the state for them. If we need to, could still have lists of specific types of node kept separately in the state for easy looping, etc.

This approach would also make it easier for a "node style" UI, for more complex input processing, as each node would be in the same part of the state and the way it needs to be displayed would only matter at the node level, not some other reference to a type elsewhere.

• [x] linkableActions
• [x] Parent ids
• [x] inputLinks
• [ ] scenes
• [x] macros

Linkable actions

• [x] Move state over to nodes
• [x] Display in correct panel (not always left)
• [x] Display number of input links
• [x] Display title
• [x] Only display MIDI as input option in dropdown
• [ ] Handle other input types? Sequencer would be simple. Other ones would involve showing a value in a bar

[funwithtriangles]

Mostly fixed by https://github.com/nudibranchrecords/hedron/pull/197. Moving to 0.6.0 to be reviewed for the extra bit