[COOT] edit backbone torsions?

[Michele Lunelli]

I recently switched from version 0.4 to version 0.5.1-pre-1 gtk2 revision 1494. 
It works great, but I cannot find the "edit backbone torsions" on the 
Model/Fir/refine menu or somewhere else. Moreover, I cannot find how to modify 
general torsions.
Am I missing something?
Thanks for helping
Michele