[prefix-sharing] Cleanup.
Merge remote-tracking branch 'origin/prefix-sharing' into prefix-sharing
[misc] Added license.
[misc] Added additional documentation.
Merge remote-tracking branch 'origin/prefix-sharing' into prefix-sharing

Conflicts:
	src/org/zoodb/internal/server/index/BTreeIndexUnique.java
[cleanup] Fixed merge.
[prefix-sharing] Removed obsolete methods.