PDB import: Improved code to guess element from atom name. This fixes issues in correctly detecting hy drogen atoms for some cases. Add support for click events on custom meshes Deprecated atomDoubleClick/atomClick events in favor of click/doubleClicked to make it clearer that th e target of the click event might be objects other than atoms. Simplified the picking results object. The picking results now provides the position of the clicked ob ject as the pos() property. It is no longer required to transform the atom position by the symmetr y transformation matrix when displaying biological units. Support for loading multi-model pdb files. Added functionality to superpose two structures using least-square fitting