* upstream/master: (91 commits)
  fixed #2613 (#2623)
  Add MathSciNet as ID-based fetcher (#2621)
  Add icon + color and description to groups (#2612)
  Fixed wrong logger import (#2618)
  Cleanup window has a scrollbar now. (#2614)
  Added the locale to a newly created class
  Move ExportComparator and CustomExportList to the correct package (only used in preferences)
  Fixes displaying of Mr DLib recommendations (#2616)
  Fix title-related key patterns in BibtexKeyPatternUtil (#2610)
  Remove OrdinalsToSuperscriptFormatter from recommended biblatex save actions (#2601)
  Update pgjdbc to new major version
  Update Dependenices String Similary log4j wiremock mockito
  Fix exception when parsing groups which contain a top level group (#2611)
  Add "Remove group and subgroups" option (#2587)
  Fix #1104: group selection is preserved under tab change
  Fix several File Cleanup + Rename issues  (#2415)
  Fixed a small error in the code comments
  Implement #1904: filter groups (#2588)
  Braces checking followup (#2598)
  Improve braces checking (#2593)
  ...