Topic/r hybrid dynamics algo

Implemented Featherstone's Hybrid Dynamics algorithm as per "Rigid Body Dynamics Algorithms" section 9.1 (composite hybrid dynamics algorithm => template in file "chda.hh").
Not fully optimized yet. Current benchmark measurements for the algorithm are :

- 100 000 loops processing
- processor: Intel(R) Core(TM) i5-4570 CPU @ 3.20GHz
- average proc time
          # 7/35 Forward Dyn joints => ~ 15 us (including jcalc proc)
          # 35/35 Forward Dyn joints => ~ 20 us (including jcalc proc)
          # 0/35 Forward Dyn joints => ~ 7 us (including jcalc proc) => equivalent to RNEA processing with jcalc.

Further optimizations implementation ongoing.