Xerces 2.12.0: Parsing Configuration

This sub task covers the changes to the parsing configuration area. Where the following bugs were fixed:

    XERCESJ-1574 - Major. Problem with detected encoding for UTF-16 encoded as Unicode Little
    XERCESJ-1398 - Major. Slow growing memory leak from XMLEntityManager.RewindableInputStream

through the following revisions:

Revision 1363647 - Fixes XERCESJ-1574.
Revision 944964 - Fixes XERCESJ-1398

These changes had dependencies on previous revisions such as 581487 and 443089. However, the JDK has its own buffer allocation mechanism and a modified Entity class. The update therefore will go without the buffer pools and changes to the Entity class as in the Xerces code base.

Besides the above, in the last revision (1513559) there was an improvement in the way parameter entity expansions were counted. In the JDK, there was a comprehensive revamp on the design and implementation of various limitations as reflected in the Java Tutorial: Processing Limit (https://docs.oracle.com/javase/tutorial/jaxp/limits/index.html). As a result, the revision (1513559) is not needed in this upgrade.