Improve handling of compression spring Force_2 > Force_Solid

[grumpyinca]

As this issue is written, the math model of a compression spring allows values corresponding to the spring being deflected below the solid condition so as to avoid the numerical search difficulties associated with limiting deflection at solid. Multiple alerts are triggered in this situation.

Should there be an FDCL constraint relating Force_2 and Force_Solid ? Should the effective value of Force_2 be limited at Force_Solid ? Should the effective value of Force_2 become NaN beyond the solid condition and thus impact all dependent calculations ?