Stereo in a subregion: Minor wording change
Minor variable name and other cleanup
stereo_corr: Respect user pref for LaplacianOfGaussian value
stereo.in: Parse correctly --corr-search -100 -100 100 100
all: This is post ASP 2.1.0
RPC: Allow reading of XML files from Pleiades and Astrium

They have slightly different XML files with different tags. They also
have a neat inverse model.