Create a Stair
The command will prompt for 2 points
Start and direction of the stair.
Stair objects have no properties or options.
A stair object has to be connected to a Smart-Object that will define
its geometry and attributes.
In the default database there are 3 types of stair smart-objects :
L Stair : Concrete stair L shaped
U Stair : Concrete stair U shaped
G Stair : Generic stair able to turn around from 0 to -180 to +180 degrees supported by steel or wooden frame