Apply calibration to QuickLook images

[hsuyeep]

The imaging can be improved with a calibration. This can either be generated occasionally (say once a day/few days) and transferred to a place accessible to atv, or can be transferred occasionally online from the calibration and imaging pipeline via a dedicated socket.

• As a first implementation, the calibration vector from a past observation will be parked on disk and the mechanism to apply it will be developed in atv.
• The complex gains shall be made available in a text file with 3 columns: Antenna number, real, imag.
• The file shall be named YYYYMMDDTHHMMSS.cal.

[hsuyeep]

Added the actual calibration code to atv.py. Need to monitor the folder where calib. solutions would be placed for any new data based on the filename, and apply if possible.

[hsuyeep]

Moved to the aartfaac-tools issue tracker. Closed this issue here.