Feature request: Allow user to rotate the primitive

[raindropsfromsky]

Now we can scale some primitives, and we can move all primitives. But we cannot rotate them in an intuitive way:

1. The rectangle can be rotated jerkily, with multiple keystrokes of R key.
2. The regular polygons (derived from the circle) cannot be rotated.
3. A polyline cannot be rotated.

Desired:
Let the user rotate the primitive like the rest of the Blender:

1. By dragging the mouse
2. If the CTRL/SHFT key is pressed while dragging the mouse, modify the rotation behavior.

Note that the center of rotation does not have to be set: The user can always drag the rotated object to the correct place he wants.

[jayanam]

Will think about 1-3.