twiss broken

[iagapov]

undulator transfer map order 2 by default. Twiss does not work (standard sase_tdp.py script)

[sergey-tomin]

fixed. There was no check on the condition - energy == 0, in that case there was division by zero in weave module, that is why it returned NaN.

Also added the check on the condition - lperiod == 0,
fixed like this:
if energy == 0 or element.lperiod == 0:
transfer_map.order = 1
....
else:
transfer_map.order = 2
....