Re 6687 MantidEV menubar, show UB

Implemented the menubar item View->ShowUB.
The UB matrix is displayed using g_log.notice(),
both in the internal "Mantid" format and in the
external "ISAW" format, along with the lattice
parameters.

Refs #6687
Merge branch 'feature/6687_MantidEV_menubar' into develop