Improve or rethink "Interpret as", "copy ID" functionality

[amund7]

Snipped from the model3 forum thread, where I tried to explain how to use these buttons. It's quite obvious that this is not exactly user friendly in it's current state:

Now the 'copy ID' and 'interpret as' buttons need a packet to pre-exist so it can be selected, but with a model S log (or load a model S log before the 3 log) you could do:

• Select a known packet / with description in the left pane
• Click 'copy id' (button will now change into that ID)
• Click a blank/unknown packet ID
  Repeat fiddly bits:
  Fiddly bit 1: Unselect and re-select the CAN ID in the left pane again (to force refresh the graph and signals)
  Fiddly bit 2: Might have to reload the file, or click the << or >> to load the next/previous file in that folder, to stream some new data.

Ideas:

• create a pulldown that lets you select any known packet, regardless if it has been recieved yet, also across model S, X, perhaps DBC files ?
• create a more intuitive way to interpret as bytes, 12-bit, 10-bit etc. Comma.ai has a super intuitive click&drag in the bits display to place a signal from/to any bits.