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* Remove ColumnShiftTable from __init__.py,
Now you must import ColumnShiftTable not from django_tables2_column_shifter but
django_tables2_column_shifter.tables
* Support for bootstrap4
* Reorganize templates for ColumnShiftTable
* Add bootstrap4 support to testproject.
* Less environments in tox- tests only for last minor django-tables2 versions
* Replace glyphicons via inside images from static.
* Sort imports by isort.