Fix an error in the dependency resolution due to a signed/unsigned comparison. See #285.
Fix an error in the dependency resolution due to a signed/unsigned comparison. See #285.

Also added some diagnostic output to the dependency resolution algorithm.

nazriel/dub,Abscissa/dub,Abscissa/dub-data-mod,gedaiu/dub,schuetzm/dub,D-Programming-Language/dub,dreamsxin/dub,p0nce/dub,rjframe/dub,jeanbaptistelab/dub,alexeibs/dub,jelmansouri/dub,xentec/dub,Flamaros/dub,grogancolin/dub,y12uc231/dub,Geod24/dub