Remove commented-out code
planet_visibility_tonight(): return azimuth where planet becomes (in)visible and of rise/set

* planet_visibility_tonight(): return azimuth where planet becomes (in)visible and of rise/set:
  * all new dummy variables are optional:
    * plazs(1:2): azimuths where planet becomes visible and invisible
    * ras(1:5):   azimuths of Sun and planet rise
    * sas(1:5):   azimuths of Sun and planet set