Jmol view of PDB structure files embedded in Classloader Jars

CLASSLOADER filesource retrieval was introduced in Jalview 2.4, but this has not been tested thoroughly for the retrieval of pdb structures from the classloader in JalviewLite.

A potential bug may have to be fixed in AppletJmol - there is currently no means of storing the fact that a PDBEntry must be loaded via the CLASSLOADER in the StructureSelectionManager.

To fix the problem for 2.4 release, the JalviewLite Loadingthread was hacked so that CLASSLOADER retrieved structures are always treated as URLs... rather than fix the above bug (see TODO in AppletJmol notifyFileLoaded method). This hack may not work when viewing structures fromt the ClassLoader with Jmol (have I said this enough times yet?)