Retry merge folder rename if it doesn't work for the first time after one second.
Improved Depth of Field Effect

Depth of field now works as it should, with objects being blurred
proportional to their distance from the focal point of the camera. The
blur is also gradual to be similar to how our eyes work.
Make it possible to become op on a headless server.

The config file contains now a one time authorization key which can be used
to get op rights on a headdless server.
Merge PR #1427 by @flo - fixes #1403 (save game crash)
Merge PR #1429 by @IWhoI - depth of field
Add CommandParameter annotation on a new command
Update readme with new multiplayer section + new credits entry, and fix up gradlew start to not overwrite config.cfg
Update networking libraries
Updated protobuf binaries to 2.6.1
Re-generated protobuf java files with compiler v2.6.1