configure: This is post ASP 2.2.2
RELEASEGUIDE: Minor clarification
.gitignore: stereo_mpi --> parallel_stero, last holdout
Support corr-seed-mode 3 using sparse_disp
sparse_disp: Fix for small images
orthoproject: Introduce parallel rasterization
orthoproject: Use pointer instead of shared_ptr
Corr: Tri: Perform cropping the same in both steps.

This reduces code in stereo_corr by 20 lines. This also reduces an
extra ImageViewRef inside stereo_tri.