Group self-selection

Lets students create and select groups.
Lets students create and select groups.  Features:
Students can create groups, give them a description and set them password protected, if wanted
Students can select and join groups
Supervisors may be assigned to groups
Teacher can export course group list as a csv-file
Full compatibility with basic Moodle groups: groups may be created by other means if needed, supports group assignment submissions etc.
Many thanks to all contributors for this module, including original authors Petr Škoda and Helen Foster and previous maintainer Pirkka Pyykkönen