This patch changes vertex group and material group user interface in the following ways:

Vertex groups:
-if there's a selection, it will get assigned to the vertex group in case the user creates a new vertex group

Material groups:
-same as vertex groups except for material this time. Note that there's still one issue to fix. It should not create two material groups if there's no selection. I will fix this soon.
-a new button to make current material as "single user" to allow fast creation of new materials. Note that the color picker found in the UI is excellent for distinguishing the different groups.