Bug#946263: openbabel: package v3.0.0

[Drew Parsons]

Package: openbabel
Followup-For: Bug #946263

Probably the installation should be updated to multiarch,
i.e. install the library to
  /usr/lib/${DEB_HOST_MULTIARCH}/libopenbabel.so 
not
  /usr/lib/libopenbabel.so