Add linux protobuf compiler and make the grandlew task runProtobufLinux working.
Tweak task name to avoid ambiguous "gradlew run"
Make the isChunkValidForRender check a lot faster.

Half of the render time was spent to check if a chunk is valid for render.

By precalculating this value when the chunks change, the frame rate
increases for me at a certain world with view distance ultra from
about 40 to 50 FRPS.
Merge PR #1383 by @flo - chunk optimization (commit redo)
Fixed an issue which could have caused the FPS to stop updating.

The issue was that the resolution of the getRealTime values was so bad,
that it couldn't be used on all PCs for checkin when enough time has
elapsed.

This patch also changes it back to updating each frame for the following
reasons:

- The FPS number is already an average so usually the value doesn't change
  by much.
- Any large FPS changes should be eliminated by us in the long run
   -> there should be no spikes
- You can see the results of what you do instantly
   -> you don't need to wait for a half second
- You don't miss performance drops that occured only at a few frames
- If the numbers update so slowly it looks like the game is having
  issues to update the UI
Merge PR #1382 by @flo - FPS display fix
Mark chunks as ready in the tests.
Fixed restore of uncompressed chunks.

Storing uncompressed chunks is a feature that is disbled by default.
A test showed that it was broken.
Merge PR #1385 by @flo - test + storage fix
Add module to readme lineup plus tweak a little Javadoc
Minor refactoring, added TODOs and references to open issues.
Fixing NPE in DelayedActionSystem.
Fix Rect2i.encompasses()
Small subset of hopefully uncontroversial changes from PR #1108.
Merge PR #1392 by @emanuele3d - some architectural fine-tuning
Merge PR #1386 by @emanuele3d - todo notes for the future
Fix NetworkOwnershipTest unit tests
Use headless env. for testing
Increased class-level javadoc, renamed some launch argument variables, now handling command-line usage requests.
Readme tweaks and tiny javadoc addition