bug fix with the initial size of the user definitions plugins

Bug fix in PreferencesSettins dialog

viewer are no longer plugins.
Improved significantly the ergonomy of the periodictable viewer
The user can now performs several atom selection and transmutation.
Improved the atom list widget
Fixed several bugs
Added new icons

viewer
Bug fix when closing a lugin pane
Bug fix with DL_POLY converter plugin

Improved the ClassRegistry import mechanism (avoid conflict with distro
module with the same name)
Improved the performance of the molecular viewer
Removed unused import
Bug fix in QVectors widgets

Bug fixes related to those unit tests.
Improved the AtomsList dialog to keep track the order in which the atoms
are selected.

Relocated several packages

Factorized the set_data mechanism for IWidget based classes

Bug fixes with user definition related widgets

Bug fix that was making the sphinx-build very slow

Many bug fixes related to ud

The temporary job script files are now also saved when running a job
from the GUI

Added a specific logfile for each launched job
Improved the JobControllerPanel
Removed the global logfile toolbar button
Removed the 'info' JobStatus entry
Removed unused Plugin.has_parent method
Bug fixes

Moved the converters to a specific menu
Reintroduced the __setitem__ for the ElementsDatabase
Reintroduced and refactored the PreferencesSettingsDialog
Refactored the PeriodicTablePlugin
Added new icons
Refactored the Icon class

directory
Bug fix due to the change from configurators to settings class variable
for IJob derived classes
Reintroduced and fixed JobHelpFrame class

conflicts
Refactored many GUI related module to make the main app restartable