Benchmarking of popcnt.
Added a list of project forks.
HPPC-88: added get(key,defaultValue) to somehow support custom default values and potential read-only concurrent containskey/get conditionals.
Updating CHANGES with HPPC-88
Updating CHANGES with HPPC-88
Clarified JavaDocs in a few places.
Adding 0.5.3 entry.
Move HashContainerUtils.java from templates to java, fix HPPC-90