hide all but mapped coordinates in Jmol view

Currently, Jalview only provides the option of hiding chains with no mapped sequences (in the View menu).

This is not sufficient for highly modular macromolecular structures, where one or more domains are often analysed independently of the rest of the structure. In this case, Jalview should provide a 'mapped regions' only option, which additionally hides portions of a chain that have no associated sequence coordinate.