gdal_list_corners fails on venus gtdr.tif (lat>90)
dem2rgb and others: maybe NDV should be independent of band selection
dem2rgb: prominant warning if resolution not known
dem2rgb: should be operable with resolution in absence of origin
run erosion several times for outline tracer
gdal_merge_simple: usage text wrong?
beveller is inefficient (maybe O(N^2))
don't use %f, use %g with the right number of digits
several inputs for contrast stretch
manual min/max for contrast stretch
better error message for NDV>255 in contrast stretch
expose options for fuzzy rectangle bounds finder
outline tracer should call OGR_G_IsValid on result
