Avoid C++ style streams

As Thiago wrote: qDebug("actionNew") also works.  The current policy is to avoid
C++ style source code as much as possible.

Signed-off-by: Henrik Brautaset Aronsen <subsurface@henrik.synth.no>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Add logic to switch views

Rename the 3 main widgets in the Qt mainwindow.

Wire view menu options to the setVisible methods of same.

Signed-off-by: Amit Chaudhuri <amit.k.chaudhuri@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>