[WIP] MDTraj analysis wrapper

[MBartkowiakSTFC]

Description of work
This PR introduces a proof-of-concept analysis run where and MDANSE trajectory can be used as input for MDTraj.

mdtraj.Trajectory and its underlying Topology object are both created in memory from an instance of MDANSE.MolecularDynamics.Trajectory.

At the moment the main effort of enabling an MDTraj analysis in MDANSE is adding code that will convert the output of the analysis into a structure that can be written into an .mda file.

Fixes

1. Added functions for building an MDTraj.Trajectory from an MDANSE Trajectory.
2. Added MDTrajAnalysis, MDTrajAnalysisConfigurator and MDTrajAnalysisWidget to enable basic parameter input for MDTraj analysis runs.
3. Implemented writeout function for hydrogen bond statistics using the Wernet-Nilsson method: https://www.mdtraj.org/1.9.8.dev0/api/generated/mdtraj.wernet_nilsson.html#

To test
Try running the only possible MDTraj analysis on different input trajectories.