DOT importer ignores edge weight and .gv file extension

[Tobias]

DOT importer has two problems:
1. the standard extension for graphviz dot files is .gv and not .dot. but the importer doesn't understand .gv
2. edge weight attribute is ignored on import
Example markup:

digraph Test {
 label="Test Graph";
 comment="This is a test graph.";
 id1-> id2 [weight=2];
}

Furthermore, the importer could use graph name as project name, label as project title and comment as project description.

[Mathieu Bastian (mathieu.bastian)]

I've fixed the problem with edge's weight and GV extension.

However on the small example you show, the "label" and "comment" lines are messing the importer for some reasons, and the following edge line is not recognized. Our importer is far from perfect and the language has many variants.