Support '' style escaping of quotes in Newick files

Newick tree files that contain nodes that include two consecutive single or double quotes in their names are currently not properly imported by Jalview.

For example:

'Syn_RCC307_5.3_3d''|CK_Syn_RCC307_2042'

raises an exception in the jalview.io.NewickFile parser.

The "''" in this case is generated by the NewickFile.print() method to escape node names that contain a ' - it's worth noting that this 'double-quote' escape convention (where a '' should be interpreted as a single ' in the name) is not necessarily standard procedure for NHX format, and it should be verified/qualified in the documentation.