Replaced gaussian gain function with Airy disk in survey.py.
Made Airy gain function a keyword option; added functionality for pointing files.
Implemented numpy arrays for airy disk gain calculation and fixed unit conversion issue.
Added capability to include independent tobs/gain for individual beams via pointinglist file.
Small change in survey.py: os.path.dirname(__dir__) to __libdir__
Joe's pointinglist additions, now merged

dosurvey/survey have been edited to take a beam pattern