This repo provides some dependencies needed by libactpol and thus by
moby2.

sla_refro-moby2-1: a C-wrapped version of a single routine from the
open-sourced Fortran version of slalib.  Provides library slarefro for
libactpol.

slim_v2_7_1-moby2-1: a patched version of libslim.  This fixes some
bugs in the handling of 8-bit integers.

sofa_20180130: The stated version of libsofa (astrometric coordinate
conversions), but with our own Makefile added to compile the right
kind of shared library.


For sla_refro and sofa, it's enough to

  export PREFIX=$MOBY2_PREFIX
  make
  make install

But for libslim you'll need to configure like this:

  ./configure --prefix=$MOBY2_PREFIX --with-zzip
  make
  make install