Improved parameter determination link budget

# Feature
## Desired Behavior / Functionality
Let the user determine modulation, BER (bit error rate), and desired link margin so that the required S/N ratio can be determined.

## What Needs to Be Done
Currently the radio and optical link budget modelling use constant values for the required BER, required S/N ratio and S/N margin. In reality the desired BER and modulation determine the required S/N ratio. See for example, this table for the relationship between modulation scheme and S/N ratio for a BER of 10E-5. Similar tables could possibly be found for other BER's and for the optical communication as well. In which case the required S/N ratio could be determined instead of being set as a constant.

_From Radio input based on Kirkpatrick, D. (1999). Space mission analysis and design (Vol. 8).
J. R. Wertz, W. J. Larson, & D. Klungle (Eds.). Torrance: Microcosm._

## How Can It Be Tested
Can be checked by hand