Decimal to Fraction

Hi all,

I have added a new algorithm. It doesn't have a proper name, so I rather called it using what it does.
It is an [algorithm to convert an arbitrary decimal value to a fraction](https://sites.google.com/site/johnkennedyshome/home/downloadable-papers), with respect to a custom accurary.
I included references to the original paper, for your perusal.
Tests have also been included, as usual.

PS: Also brougt a tiny little fix to the Dijkstra algorithm, a comment was wrong in the test file, I fixed it.

Regards,
Roland.