Code review comment for lp:~jan-ellenbeck/openwns-rise/LTEantennaAndSpeedUp

- Added a 120-degree sectorized antenna according to LTE draft 3GPP 25.814
- Added two speedups for the calculation of static twodimensional antenna pattern gains that reduce simulation time in my scenarios by aobut 30%:
   1) Precomputing antenna pattern avoids wns::Ratio::from_factor() calls on runtime.
   2) Reducing angular precision from double to float and avoiding unneccesary object
      constructors/destructors saves additional computation speed when calculating the
      angle.