Added GetMemUsed methods; Fixed bug in TTable::AddJointRow
Added memory usage getter for TStrHash and TBigStrPool; Added print size to TTable; Fixed Bug in TTable::AddJointRow
Add optimization to QSort to handle the case when a lot of rows are the same.
Merge remote-tracking branch 'upstream/master'
Moved GetWeightedPageRank to centr.cpp, added benchmarks folder