Fixed an issue in the mmCIF reader for files starting with a ligand only chain. Before the first atom was stored in its own residue and the remaining atoms in a second residue. Happend for PDB entry 1AGA.

Hetatms are potentially skipped but if they come with an ANISOU record,
ost expects them to be there. As a solution we simply increase the
permissiveness as we already do it when having the calpha_only option
active.

solves a variety of problems that gcc (mainly the c++11 as default)
throws at us.