Iterative Deepening Depth First Search

Hi, all

Added a new graph search algorithm, named [Iterative Deepening Depth First Search](http://en.wikipedia.org/wiki/Iterative_deepening_depth-first_search) (Yes, *what a name!*). IDDFS, for short.
This implementation is generic, as usual. I included some comments, provided map handlers for reference, and tests, as well.

PS: Also added slight typos fixes for some previous commits :) Sorry for the noise.
Cheers,
Roland.