Resolve "Implement circular symmetric beams"

Implement circular symmetric beam functionality in EveryBeam, please note:

• Both EVLA and ATCA return a DishTelescope. Subtle differences between these two can easily be implemented in another derived class in a later stage.
• There are, as yet, not relevant Options to be set for Dish telescopes, correct?
• Compatibility with WSClean will break, since the input ordering for the Load method changed

Closes #41 (closed)