Merge branch 'add_python' into 'master'

COMPILE

Makefile.am

c_utils/walltime_c.c

c_utils/walltime_c.h

configure.ac

fortran/sharp.f90

fortran/test_sharp.f90

libsharp/sharp.c

libsharp/sharp.h

libsharp/sharp_almhelpers.c

libsharp/sharp_almhelpers.h

libsharp/sharp_core.c

libsharp/sharp_core_inc.c

libsharp/sharp_cxx.h

libsharp/sharp_geomhelpers.c

libsharp/sharp_geomhelpers.h

libsharp/sharp_internal.h

libsharp/sharp_legendre_roots.c

libsharp/sharp_legendre_roots.h

libsharp/sharp_mpi.c