Markov: Chain: use qualified import for Data.Map
Markov: Chain: implement chain probability as Int

Warning: this breaks other modules.
Markov: Examples: implement integer probs
Monkey: Analyzer: use integer probabilities
Markov: Chain: stop when no states are accessible

Previously, an error was thrown when no accessible states were available. Now
we don't guarantee that walks last the given number of steps, but we don't fail
in that ugly manner.
Merge pull request #1 from spyked/int-probs

Int probs