* Markov.Chain.add_weight/4 would return a fresh new markov chain, instead of using all of the previous values of the chain that was being modified. This would result in resetting the reply_chance value to the default of 0.01. * Add tests to make sure this doesn't happen to add_weights in the future. Signed-off-by: Alek Ratzloff <alekratz@gmail.com>