CNTK: Fix compilation issues due to BoostFS changes.

Things need to be cast to strings before I can add a suffix.
Core: Implement Affine Epipolar Rectification solver

This also publishes it as an option in all the sessions.
WIP: Convert stereo_tri to how I want the API to work like
WIP: StereoSession drop LUT
WIP: Move some StereoSessions over to new API style
WIP: Attempt some more to finish the API change
Sessions: Add TestInstantiation

Makes sure that at least the sessions compile and define the types we
need. This is to make the developers life easier so they can look at
errors here instead of errors *20 inside the Tools directory.
stereo: Remove templates in calls to stereo_triangulate

Easier to read and less to type.
stereo_tri: Remove more unnecessary code
stereo: Have left crop win be defined by the L.tif, not left img.

The new design allows the alignment options to change the size of L
and R tifs.
Sessions: Add NadirPinhole session

This a session specifically for satellites that are modelled by
pinhole camera models but look straight down at earth from an orbit.
WIP: Possible solution for supporting RPC map projection in stereo
Core: Have homography alignment crop to active areas of image

To help signify to all the developers that this is the new operation
... I changed homography_fit to homography_rectification. It kinda
meets the naming pattern I set in affine_epipolar_rectification.
StereoSessionDG: Bug fix
Modify code and doc to reflect left and right transforms
DemDisparity: Make it work for new hom and affine epipolar changes
I do care
stereo.cc: Correct handling of left-image-crop-win
stereo_tri: Rm stray comment
DG: Add RPC Map project test