Koloboke 0.6.8

A maintenance release, no API changes.

• Fixed #43 (Dependency containing Nonnull/Nullable annotations made optional)
• Fixed #45 (Memory leak in HashObjObjMap implementations, clear() method)

API Javadocs:

• For Java 6 or 7 in Java 6 style
• For Java 6 or 7 in Java 7 style
• For Java 8

Download binaries:

• For Java 6 or 7: API jar, impl jar
• For Java 8 or 9: API jar, impl jar