Extreme resize test
oiiotool: More careful selection of filter for resizing.

Previously, in cases of large maxification (zooming in), the entire
filter could fail to cover any source pixels, resulting in black grid
lines in the output.  Now we make sure that when the destination pixels
are higher frequency than the source pixels, that the filter is
constructed to be wide enough in "source pixel space."
More careful resize filter size selection for maketexture.
Merge pull request #544 from lgritz/lg-resize

Clean up resize filter selection issues