Java .Blend update to Blender 2.81.16

Another update of Java .Blend to reflect changes in Blender release 2.81.16.

Blender switched to a faster release cycle, now releasing a new version every three months.

Changes to the file format are rather insignificant, but files of release 2.81 are no longer binary compatible with files of release 2.80.
This is odd, because the minversion of files in version 2.81 still refers to 2.80. So I asked on the blender dev mailing list,
what the actual meaning of minversion is. I’ll let you know, when I’ve found out - might have to change the approach for Java .Blend then.