It was REAL and using REALs as array indices is a nonstandard extension
of Foertran.

This looks a little bit nicer.

I put this in in a slightly dirty way as I use a GO TO. But I
think it is ok.

This lead to wrong symmetry operations

I don't know whether there was a problem or not.
But I think that this commit makes the routine a
little more stable.

spg_gen became a limiting code part for large unit cells as
parts of it scaled with the number_of_atoms^4. I rewrote
certain parts of it in a more efficient way. Better scaling
now.

I hope I didn't damage anything.

Markus Betzinger authored Apr 26, 2016 and Ingo Meyer committed Apr 26, 2016

Based on v0.26 hybrid branch