#266 site coordinates

[Willem van Straten]

Currently, the coordinates of an antenna are set by calling Telescope::set_coordinates (defined in Base/Extensions/Telescopes.C) which calls Site::location (defined in Util/resources/Site_location.C) which calls either Tempo2::observatory or Tempo::observatory.

The dependence on tempo/tempo2 for antenna coordinates should be decreased by using the ITRF extension that is part of the PSRFITS definition, if available.