Modified a bit the validate method of UserDefinition derived classes

plugin like before

trajectory to define putative complex

IWidgets subclasses according to this

anymore.

Removed the old unused UserDefinitionsPanel

IUserDefinitions interface when setting an ud

configurator

for all the same type of molecule

Bug fix in McStas analysis

Update the setup with automatic documentation build

Added a new icon for displaying MDANSE API

Bug fix in conf.py sphinx configuration file

Bug fix that was making the sphinx-build very slow

warnings with sphinx

Bug fix related to pickle mechanism and User definitions

Bug fix in UD_STORE

Reduced the size of PDB example file.
Added the generated functional tests for all MDANSE analysis.
Bug fix in spatial density cython file

Improved the generic converter
Reintroduced and refactored rigid-body trajectory analysis
Implemented the dipole autocorrelation function analysis

Many bug fixes related to ud