#51 Integrate real op2calltree that imports call graph

[Anonymous]

There is an oprofile 2 call tree implementation available at:
wget https://code.monotone.ca/p/monotone/source/file/h:net.venge.monotone/contrib/op2calltree.py

Unlike the existing code it accepts data from oprof -cdf and imports callee / call graph information. Call counters, alas, are not available, but still it it actually usefull, unlike the one provided with distribution