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 visualizations

...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.