Reorganisation

• Factor vanilla JS out of JSX, use nicer folder structure (Closes #21 (closed))
• No more loading screen, make individual components respond to "loading" state of metadata (Closes #23 (closed))
• Make LinesTable the "main page", can click "choose decays" to get to DescriptorsSearch (Closes #22 (closed))
  • All Routes update the same global application state: add/remove decays, configure DecayTrees and choose lines/data in any order!
• Use appropriate input elements for editing different data types in TupleTool configuration (Closes #10 (closed))
• Configure individual DTTs (Closes #26 (closed))

To do:

• Make sure changes to a DTT are only committed on clicking "Save changes" (probably requires making a deep copy somewhere)