Release 3.3.9

Release 3.3.8

Release 3.3.7

Release 3.3.6

Release 3.3.5

Release 3.3.4

Release 3.3.3

Release 3.3.2

Merge pull request biolab#1135 from ales-erjavec/win-install-update-pip

Windows installer: update pip on target system if required

Merge pull request biolab#1129 from astaric/fixups

[FIX] OWRank no longer crashes when additional learners are available