Improvements

[Sujay-Shankar]

• Reorganize code
• Make dashboard attributes such as the currently displayed spectrum accessible
• Overhaul callbacks to be more readable and fast
• Add grid info property
• Dashboard visual improvements
• Restore and extend old nearest point functionality
• Add ability to bulk instrumental broaden a grid
• Other improvements, probably

[gully]

We should resolve these minor conflicts so we can merge this

[gully]

Wait, is this PR a duplicate of #86? It only has 3 new commits compared to that PR? I suspect we could rebase this PR to make it clearer.