Drawpile 2.1.7 release

Version 2.1.7 is now out. Only a few changes in this version. The most important one is the properly patched Qt library in the Windows version, which should fix some tablet problems.

Other changes in this version are:

• Added Ukranian translation (thanks to Yuri Chornoivan)
• Fix navigator not updating correctly on canvas resize
• Improved join dialog:
• Removed list server selection dropdown. Instead, all listings are shown together in the same box
• Replaced the filter buttons with labeled checkboxes
• The session list box can now be hidden by simply resizing the dialog
• The dialog now remembers its size