Corrected MDI

Today we continued with MDI implementation that we started yesterday and which was not correct. It was exhibiting some inconsistent behavior.

The graphics scene and graphics view are implemented using different classes for each. The MDI implemented seems faithful now, whilst it has no actions connected to it.

The arg() function of QString class is being used to automate the generation of file names whenever a new file is generated. Let me show this:

static int num = 1;
QString fileName = "Document %1".arg(num++);

Now every new file will have a unique name like Document 1, Document 2 and so on. Anything starting with "%" is treated as the variable to be worked upon by arg().