Implement a cache of logically equivalent MatchExpressions and Intervals. Take into account the findings in MatchExpression and Intervals in CBR  and the prototype in https://github.com/10gen/mongo/tree/s-95255-ce-cache, specifically these two files: ce_cache.h, ce_cache.cpp

The cache will be at the level of individual query optimization requests, and will contain nodes from alternative plans for the query currently being optimized.