When importing a PDB file, the user has to be in the 'OBJECT' mode. With the changes
in the code, this mode is automatically set before the PDB import. No error message
should appear when the 'EDIT' mode is still active.
Comments
========
This is the fusion of the 3 atomic blender addons from Blender 2.79:
1. PDB (I/O addon for .pdb files, was in trunk before)
2. XYZ (I/O addon for .xyz files, was in contrib before)
3. Utilities (panel for modifying atomic structures, was in contrib before),
into one single addon called ‘Atomic Blender PDB/XYZ’.
