all: Drop shared_dynamic_cast for dynamic_pointer_cast

Boost 1.53 dropped shared_dynamic_cast. Dynamic_Pointer_Cast is the
more general function and already exists in the older boosts.
stereo_corr: Cleanup debug info
stereo_mpi: Try to create the soft links at each step
stereo_corr: Make local-homography a command line option
stereo_mpi: Fix a bug with --threads
stereo_mpi: Minor comments
stereo_mpi: Add timeout for correlation option
dg_mosaic: Strings and array can be compared simply with ==
InterestPointMatching: Rm pseudo image copy
dg_mosaic.py: Closer to python 2.4
dg_mosaic.py: Make it work for python 2.4, 2.6, 2.7
Core: Added parallel interest point matching

This is not as fast it could be as I'm by default mutexing all
interaction with the camera model. (This is because of ISIS.)
build_vw_asp: added build script
build_vw_asp: fix git commands and number of processors
build_vw_asp: specify gcc4.7