Re #6846. Moved WindowHelper to be in MantidQt/API
Re #6846. Added namespace to HelpWindow.
Re #6846. Changed HelpWindow to be a singleton.
Re #6846. Moved the algorithm help to use qt assistant.
Re #6846. Removing unimplemented methods to help windows linking.
Re #6846. Trying to fix the windoze builds.
Re #6846. Trying to fix the windoze builds.
Re #6846. Adding more logging and searching for windoze assistant.exe.
Re #6846. Fixing messed up ifdef.
Re #6846. Fixed bug in Load help button and HelpWindow method.
Merge remote-tracking branch 'origin/feature/6846_qtassistant_singleton'