Fixed missing imports

Also some minor formatting changes.
Simplified slice syntax

Just makes the code more readable
Fixed colorbar bug

Plotting with a log intensity scale when all the values were 0 or
negative triggered exceptions that affected other functionality such as
switching axes. This mostly affected datasets where the top layer of a
3D slab, which is the default to be plotted, is outside the range of
valid data values, for example after a coordinate transformation.