Make everything work with a temporal mask

[d1manson]

Want waveforms, clusters and ratemaps to work with a temporal mask. Then implement a number of masks:

• slider/textbox for defining a section of the trial.
• slider/textbox for defining a range of valid speeds
• dial/textbox for defining a range of valid directions
• and more...?

[d1manson]

The spike aspect of this should be fairly easy to implement - just get cut.js to mask the inds for each group. ..though even that much isn't super simple.
Then you have to look at pos, but pos is already in need of some encapsulation so we should bear that in mind when writing it.

[d1manson]

With the new rewrite this could actually be done without an absurd amount of mess-making and time.