RLEDataSource
**********

=>GetNextPage logic only considers logic predicates for now
=>NOT IMPLEMENTED: Filtering with datasources is 
=>RLEWriter assumes block input to it is in order
=>RLEDataSource instatiates a new decoder for each page
	-instead decoders could have a setPage logic
	
RLEExtractLoadAndAccess
========================

=> new and delete of a RLEDecoder in a loop

AM
==
->cannot do initCursors more than once

BitWriter
=========
-> Have to do memset (which probably slows it down slightly) of buffer or else some writes don't occur properly (see MultipleColumnsTest.cpp)
-> cannot write negative values

BitReader
=========
->Cannot read negative values

DeltaPosBlock
=============
->init calls bit reader to read common values

IntDataSource
=============
-when page sorted, we do lookup on am fine, but I walk down the whole page to find the values that start ot match pred (some type of search would be better)