CubeSum should report continuum flux

[teuben]

In "runa2" the flux is never computed. Summing the fluxes of the source detections will most likely not be good enough. Example is test253_cont.
The two sources add up to 0.294 Jy, but enclosing a polygon around the main emissions looks more like 0.35 (disregarding the obvious missing short spacings which biases everything)

CubeSum currently doesn't see continuum and forces the units to be Jy.km/s, that's wrong as well.

[teuben]

A patched version "1.1.0-issue34" has been commit-ed. This needs to be rebased with the python3 branch eventually.

No patch to admit2.py (run2) has been yet. That should be done in due time as well.

The flux in test253_cont is now reported as 0.327330... Jy