Fix incorrect ReleasePrimitiveArrayCritical call
Merge pull request #46 from sunxiaoguang/fix_jni_release

Fix incorrect ReleasePrimitiveArrayCritical jni call
expose ability to set compression level for LZ4-HC introduced in lz4 r113
cache constructed HC compressors
Add test case for customized-level compressor.
Added hashtable caching for Java Implementations.

Quick benchmark shows a 4% performance gain.
use ThreadLocal for caching