Reading the BIRD data from prd-all.cif.gz which doesn't contain any
compound would result in a compound lib filled with dummy compounds and
atoms, containing no useful data. This commit skips compounds with no
_chem_comp.id (key data item) and non-loop atoms without an
_chem_comp_atom.atom_id, with a warning.
The result of reading prd-all.cif.gz is now an empty compound lib.

wrong branch, big sorry

This reverts commit e77d08a6.

This reverts commit bf46ad1a.

Conflicts:
	modules/conop/src/compound.hh
	modules/conop/src/compound_lib.cc

-> you must recreate your compounds.chemlib database to activate
   this feature using the chemdict_tool

git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2726 5a81b35b-ba03-0410-adc8-b2c5c5119f08

git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2724 5a81b35b-ba03-0410-adc8-b2c5c5119f08

Attention: The internal format of the compound library has changed.
You need to recreate the library!

git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2717 5a81b35b-ba03-0410-adc8-b2c5c5119f08

as soon as an atom is unknown, we switch back to a distance-based
connect mechanism for the full residue. This avoids problems with
residues coming from CHARMM/GROMACS and other force fields that do
not follow the naming convention of the PDB. To really become useful,
some additional changes to the compound library are required that
will be implemented in a next commit

git-svn-id: https://dng.biozentrum.unibas.ch/svn/openstructure/trunk@2714 5a81b35b-ba03-0410-adc8-b2c5c5119f08