Merge branch 'hotfix-0.1.15.1'
Merge branch 'release-0.1.16'
Merge branch 'release-0.1.17'
Merge branch 'release-0.2'
Merge branch 'release-0.2.1'
Merge branch 'release-0.2.2'
Merge branch 'release-0.2.3'
Merge branch 'release-0.2.4'
Merge branch 'release-0.2.5'
Merge branch 'release-0.2.6'
Merge branch 'release-0.3'.
Update version number to 0.3.1 and Changelog.
Fix a bug when selecting an exam from the grading mode.
Merge branch 'hotfix-0.3.1' into development.