v3.0.4 - New major release

New major release:

• New BSD 3-Clause License
• Black code formatting on all Python files
• New automated test suite:
  • Added module guidata.env to handle execution environment
  • Added support for an "unattended" execution mode (Qt loop is bypassed)
  • Added support for pytest fixtures
  • Added support for coverage testing: 70% coverage to date
• Documentation was entirely rewritten using Sphinx
• Reorganized modules:
  • Moved guidata.hd5io to guidata.dataset.hdf5io
  • Moved guidata.jsonio to guidata.dataset.jsonio
  • Renamed guidata.userconfigio to guidata.dataset.iniio
  • New package guidata.utils for utility functions:
    • Removed deprecated or unused functions in old guidata.utils module
    • Moved old guidata.utils module to guidata.utils.misc, except the
      functions update_dataset and restore_dataset which are still in
      guidata.utils (root module)
    • Moved guidata.encoding to guidata.utils.encoding
    • Moved guidata.gettext_helpers to guidata.utils.gettext_helpers
  • Splitted guidata.qtwidgets in two modules:
    • guidata.widgets.dockable for dockable widgets
    • guidata.widgets.rotatedlabel for rotated label
• Other changes:
  • guidata.guitest:
    • Added support for subpackages
    • New comment directive (# guitest: show) to add test module to test suite or
      to show test module in test launcher (this replaces the old SHOW = True line)
  • guidata.dataset.datatypes.DataSet: new create class method for concise
    dataset creation, allowing to create a dataset with a single line of code by
    passing default item values as keyword arguments