I-Shape Beams with possibility of different width for the bottom and top flange

It is now possible to keep different widths for top and bottom flange of sloped I-section beams irrespective of rectangular portion.

Before Q4/2021:

Top flange width depended on B parameter of rectangular portion.

After Q4/2021:

Added bt1 and bt2 parameters for different top flange widths.

Note: For existing sections, default value for top flange is set equal to B parameter.