Merge RBTree-based Extent Map with EM Index to remove scaleability slow-downs -develop5

This is a final merge of the two features introduced to reduce ExtentMap operations slowdowns caused by a significant Extent Map.
In the end MCS operations, e.g. INSERT, bulk ingestion, SELECT must operate almost as fast as they did with an empty ExtentMap.

4 QA There are two aspects of this project:

• functionality(there must be no regression) so you need to test overal MCS functionality(pay attention to bulk ingestion running in different modes and rollbacks).
• overall speedup when used with Extent Maps(> 50MB). There is compressed extent map image(BRM_saved_em.tar.bz2) from one of customers I will share that should be used for testing. One needs to replace empty EM file with the image and compare timings for a variety of operations: INSERT, bulk ingestion, rollback, deletes. Plz note that the previous stable MCS 5 version already contains the subset of the functionality. There is another important detail, namely with the current code Extent Map takes about 5 times more then previously in shared memory, e.g. 300 MB image will now takes 1.2GB for Extent Map + 400 MB for index. We will address the extent map size after this patch.