Added a couple more SConscript files to build tools tested by autoregress.
Merge branch 'devel' of github.com:khogenso/ASF_MapReady into devel
Two more SConscript files for autoregress - needs diffimage and diffmeta
Added diffimage and diffmeta
Merge branch 'devel' of github.com:asfadmin/ASF_MapReady into devel
New option "-grid-match" to asf_terrcorr that uses tiles to match

This is code we had in there but was disabled.  Now that functionality
is available from the command-line to asf_terrcorr.  It will exit after
generating the matching grid, users will then have to use fit_warp etc
in order to complete terrain correction.  Added help info about it.
Merge pull request #168 from khogenso/devel

scons support for asf_convert, brs2jpg, diffimage, diffmeta