In the yuqk fork, fixed bugs related to the shell out string
substitutions '%%', '%s', '%h' and '%w'. The first two are broken
outright. The second two in defaulted situations.
These bugs look to exist back to v3.7 - though I tested only v3.8 beta 2.
While in the code I added two additional shell out string substitutions
in %d and %e. Where %d substitutes the directory in which the scene file
exists and %e substitutes the output image file extension.
Bill P.
