First attempt at post-pruning dendrograms.
Moved post-pruning into Dendrograms.
First attempt at merging branches.
Clean-up removal section.
Use isinstanceto check is_independent.
Merge failed leaves into siblings.
Added support for Kelvin brightness temperature units in compute_flux.
Added a print statement warning about the Kelvin interpretation.
Wrote a test for compute_flux with kelvin inputs.
Updated documentation re: Kelvin brightness temperature units in flux.
Fixed a problem with the Kelvin flux computation; now we require & use spatial_scale.
Updated the Kelvin flux test case to reflect the new (correct) signature.
Updated the documentation for Kelvin and spatial_scale.
print "blah" -> print("blah") for python3 compatibility
Introduced UnitMetadataWarning to replace the unwieldy print() statement.
Fixed the omega_beam calculation; `wavelength` now uses spectral equivalency.

Addressing GitHub comments from Adam, Chris, Erik. Also massaged the warning for brightness temperature kelvins.
Fixed the first Kelvin test case, added a new one (with frequency input instead of wavelength)
Revamped pruning scheme. Iterates until all pruning is done.
Use fill_footprint. Removed re-assigning idx.
Set recursive to False.