Revised longitudinal tracking: integrated the libintegr.py integrator suite into longitudinal tracking.
It has been benchmarked against the former 3 integration mechanisms (exactly the same numbers are obtained!).
Alongside with a few precision improvements in various parts, the libTPSA library has been provided (needed since libintegr.py supports checking integration mechanisms for symplecticity).
	modified:   BenchMark_BBresonator_longitudinal.py
	new file:   impedances/longitudinal_impedance.py
	modified:   trackers/longitudinal_tracker.py
Merge remote-tracking branch 'origin/oeftiger' into juanfem

Conflicts:
	trackers/longitudinal_tracker.py

	modified:   BenchMark_BBresonator_longitudinal.py
	modified:   beams/bunch.py
	modified:   beams/matching.py
	new file:   trackers/libTPSA.py
	new file:   trackers/libintegr.py
	modified:   trackers/longitudinal_tracker.py
	modified:   trackers/longitudinal_tracker.py
	modified:   trackers/longitudinal_tracker.py
	modified:   trackers/longitudinal_tracker.py
merging + resolving conflicts