Merge remote-tracking branch 'origin/feature/6846_qtassistant_singleton'
Remove unnecessary mention of ISIS in log message. Refs #6202
Formatting changes only. Refs #6202
Add MessageDisplay & QtSignalChannel classes. Refs #6202
Allow/disallow control over log level in message display. Refs #6202
Formatting only change. Refs #6202
Allow MessageDisplay to clea & replace contents. Refs #6202
Add light-weight message class. Refs #6202
Emit Messages not strings. Refs #6202
Hook new MessageDisplay to MantidPlot. Refs #6202

No colours and the old stuff is still in the code.
Gradually replacing custom log functions with logger objs. Refs #6202
Show results on error. Refs #6202
Remove uses of old results log QTextEdit and replace with new

MessageDiplay instance. Refs #6202
Remove console window and pipe everything to results log. Refs #6202
Add single argument constructor to MessageDisplay. Refs #6202

Allows it to be used in the designer plugins more easily.
Move MessageDisplay to MantidWidgets where it belongs. Refs #6202
Add MessageDisplay to designer plugins. Refs #6202
Allow QtChannel to filter on a given source. Refs #6202
Replace log handling in SANS window with MessageDisplays. Refs #6202
Remove Poco logging from UserSubWindow. This is now all controlled

using the MessageDisplay & loggers. Refs #6202