Revision 1303891

Bugzilla #46962: Fixed deadlock in PropertyCache.

Re-wrote the PropertyCache class, leveraging Java 1.5 concurrency features.
Implemented equals and hashCode on many Property sub-classes to make the caching more effective

Patch by Alexios Giotis, applied with the following minor modifications:
* Javadoc improvements to PropertyCache
* Factorize into new CompareUtil class code often used by equals and hashCode implementations