Dimensionless foundation stiffness moved out
Speedc now part of beam model

Minor moves here and there
Moved IrwinCorten contents to Crack, will expand Crack
Unfinished crack object, check outputs!!
Crack extension force fixed
Minor change
Merge branch 'V2.6'
Merge branch 'master' into V2.6
Merge branch 'V2.6'
Test