v0.50.3 release
- add allow robots.txt tag for /share
- fix inclusion of share.js in builds, fixes #2738
- invalidate flat text cache after login to protected session, fixes #2712
- logging improvements
- fix uploading binary data through ETAPI, closes #2667
- raise line-height in share CSS to 1.5, fixes #2671
- fixed blurred selection background color, closes #2652
- make it clear that Dockerfile needs to be run through a script
- fix importing unknown image types such as .DWG, * closes #2628
- fix param validation