#384 Monochrome output

[Frank Markesteijn]

To make UFRaw always produce monochrome output from monochrome input, change line 279 in ufraw_writer.c from:
int volatile grayscaleMode = uf->conf->grayscaleMode != grayscale_none;
To:
int volatile grayscaleMode = uf->conf->grayscaleMode != grayscale_none || uf->colors == 1;