correcting comment.
moving _sortRegisters from initCursor to initialize.
proper initializeCursor method for GatherBlock.
destructor for GatherBlock, deletes _gatherBlockBuffer
destructor for EnumCollBlock that deletes local data.
destructor for IndexRangeBlock, deletes private data
destructor fo EnumerateListBlock, deletes local data
destructor for CaluculationBlock, deletes local data.
destructor for SubqueryBlock, deletes private data
fixing arithmetic in available in GatherBlock.
fixed arithmetic in GatherBlock::skipSome
remove unnecessary and incorrect renewal of ourLessThan.
finished looking at ExecutionBlock destructors.