Additional User Control of Angle/Double Angle User Steel Table Specification

The issue here lies with the Angle / Double Angle User Steel Table Specification inputs - unlike the "Tee" input dialogue box where the user can specify the Cross Sectional Area (Ax) - the Double Angle input auto-calculates the area based on the angle dimensions. The Shear Area can be modified by the user, but not the cross sectional area. As the express purpose of the User Tables is to allow for the modifications of these values, this needs to be added so that built-up-sections consisting of double angles that are not properly evaluated under the general user table can be accurately evaluated in the "Double Angle" User Table without the synthetic modification of the area by tweaking the physical dimensions of the angle, which has impact on the calculated slenderness of the member.