new spatial filter superclass
Cache ApsectRatio.

Fixed Fft bug.
Added alot of PrintSelf methods.
DilateErode and OpenClose filters.
Translate regions, and moved copy data from region to data.
also added Make writable method to region object

DOP has changed.

to have its own coordinate system (but not used yet).
Also added difference filter as an example of dyadic filter class.

Removed any Absolute Coordinate system from region.
Added a coordinate system to Data.

This commit was manufactured during conversion from CVS to merge the
VTK 1.2 release branch.

The VTK 1.2 release tag in CVS was moved file-wise as fixes were made.
Therefore the true history of the 'branch' is gone.  Furthermore, the
CVS tag does not match any release tarball, and server-side repository
files are missing.  This commit was manufactured during conversion from
CVS to approximate the release.