Fix circular reference in Abstract filter

Abstract filter had a circular reference to the previous and next
filters.

updates #250
fixes #250
closes #250
Move allocations out of the constructor.

Allocations do not need to be done in the constructor. Fixed.
Fix data reader classes for large (>2GiB) datasets

The readers would have issues with reading large data sets. The code was written
to read the data in small chunks based on a DEFAULT_BLOCKSIZE. This results in faster
reads and more importantly, reads that actually succeed.

fixes #245 updates #245