Add m file convert

Aforementioned python script from issue #279. User can import the code into an existing python script and use the 'convertMFile' function, or can run standalone with command line input. Both ways allow the user to say if they want the chain, the logLikes, or the logTargets to be output. The default is to grab all of them and put them into their own text files. If the original m-file has name sipOutput.m, this script creates sipOutput_chain.txt, sipOutput_logLikelihood.txt, and sipOutput_logTarget.txt. User can also customize the regex expression that finds the tag identifying the chain, likelihood, target if they need special behavior.