Emcee new

Due to problems with Mikes original implementation, code duplication and poor optimization, we have implemented the emcee algorithm again trying to be as open to extensions as possible. That means, it should be fairly easy to implement other output formats for the chain or different algorithms for the step. Currently the original function is still available and the new function is implemented in emcee_hammer, in the future I expect that we can make 'emcee' a call to 'emcee_hammer' with certain options set.