Added zeroconf button in ROS env dock widget.

- Added zeroconf button in ROS env dock widget. This will set master uri
and hostname to current machines zeroconf-hostname.
Added more console output.

- External terminal widgets now print if they are started, terminated or
finished.
Added slot decorators.

- Added slot decorators.
Changed base class to QDockWidget.

- Changed base class to QDockWidget. Widget now docks in main window's
bottom area.
Added support for external process QDockWidget.

- Added support for external process QDockWidget.
Added qsci lexer api support from preview.

- Preview is now saved temporarily. Temp file is used as input for
QSciApis auto-completion.
Changed base class to QDockWidget.

- Changed base class to QDockWidget.
Changed allowed areas for stdout dock widget.

- Changed allowed areas for stdout dock widget. Now only bottom area is
allowed.
Changed DockWidget style.

- New external process widgets are now created tabified with existing
stdout dock widget.
Changed allowed areas for some dock widgets.

- Changed allowed areas from backend preview, fsm graph, and ros
enviromnet. Now they are only allowed on right dock widget area.