Added a crude version of gap detecting

Some issues include:
Hovering mouse over the interpolations puts the cover behind the
interpolation
Causes a lot of errors by trying to interpolate on undefined points
(this is somewhat minor though as you can only tell in the error output
of the console)
A single point will sometimes be between gaps, looks funny when it
shows up (should just make the gap include that point)
There’s probably a much faster way to detect gaps, I have one idea that
might work, should be O(log(n))