Re-order imports

Changed the name of the perspective package previously (by adding its
repo path as a prefix), but did not move the position of these imports
to retain alphabeticity. This fixes that.
Directly set pixel values in wave-sorted vis

...no need to go through plot() here, since the convenience of taking a
uint32 with a 16-bit range and converting it into an 8-bit color array
isn't really relevant in the context of this visualization.