Fixing some checkstyle issues.
allow to cancel world preview
add error label
ensure that only valid colors are generated
add progress percent to wait popup
Merge PR #1314 by @meniku - preview cancel option
Update readme - F1 clarification, two new modules, new contributor
parameter changes
Adding ImmutableBlockLocation for other classes to use, for example as a key in maps.
Merge remote-tracking branch 'upstream/develop' into develop

Conflicts:
	engine/src/main/java/org/terasology/utilities/concurrency/DynamicPriorityBlockingQueue.java
Merge pull request #1320 from MarcinSc/develop

Adding ImmutableBlockLocation for other classes to use, for example as a key in maps
Merge PR #1321 by @meniku - ladder improvements
Add general world timer events
Removed reflection cache flag from system config - moved to build system
Added semantic timer events again and separate event types
Base classes for ObjectFacet3D, similar to ObjectFacet2D.
JavaDoc added.
Tiered block damage, shovel, refactor blocks to common basedon templates.
Cleanup some .block comments.
Add World.getAllFacets()