Allow individual cells and arbitrary cell selections to be moved.

[ghost]

Describe the new feature being added
You should be able to move your mouse to the bottom right corner of an arbitrary selection of cells and grab that selection and move it to another location of the data grid.

How will this feature improve this extension

This feature seems like it would be expected by the typical user based on the other features that we support (e.g. moving a row or column). We would not want to disappoint someone when they attempted to carry out this operation. It is also just in general a very helpful thing to be able to do for easy organization of data.