COMP: Improve build speed for boost

SVN downloads of boost were increadibly slow, and were significantly
slowing down the build process for BRAINSTools.  Switched back
to the tarball of the latest stable to greatly improve speed
of Boost building.
ENH: Update Superbuild based on enhancements from NAMIC week.
COMP: Replace linear image list with map of lists by type.

In order to re-do the algorithm to use covariance between
image types, first we need to change the datastructure for
input images & derivatives from a simple vector to a collection
of vectors organized by type.

This is in preparation for re-writing ComputeDistributions.h such
that the covariance is computed between types of images instead of
between individual images. This will, it is hoped, remove the
error condition when for example 2 T1 images are given as input
that have very small differences.
BUG: first attempt to fix LLSBiasCorrector
BUG: crash on linux, craziness on OS X, valgrind to the rescue
BUG: AtlasRegistrationMethod: XFRM list was incorrect
STYLE: extra semicolon
Merge pull request #44 from Chaircrusher/BRAINSABC_Refactor

Brainsabc refactor
COMP: accomodate templated transform types
Merge pull request #45 from Chaircrusher/TemplateTransformChanges

COMP: accomodate templated transform types
BUG: Uninitialized class member in GenericRegistrationHelper
Merge pull request #47 from Chaircrusher/UnInitRegistrationHelperMember

BUG: Uninitialized class member in GenericRegistrationHelper
COMP: Temporary patch to get SimpleITK to build

SimpleITK is catching up the single precision version
of ITK that is available.
COMP: Need git tag from github for temporary fix.

SimpleITK needs a bug fix for working with the newest version of ITK.

Template forward parameters can not occur with typedefs.
COMP: DCMTK needs the NO_MODULE option added for the find function.
COMP: UKF did not build properly due to SEM

UKF did not specify the proper build paths for building SEM.
WIP: convert double precision type transform to single type