Allow flag for decoding methods to save intermediary results

[mekarpeles]

In order to create an example (see #14) which visually demonstrates the steps and outputs of basic/naive captcha cracking, each method which mutates the image should have an option to save its results to disk. @boyter had this in his original code.

[boyter]

Sorry for hijacking but it emailed me when you did the @boyter never expected something like this to come from some little article I posted!

[mekarpeles]

No problem! Thanks for your hard work with the original post (preserved here: https://web.archive.org/web/20121012023114/http://www.wausita.com/captcha/)

[boyter]

No problem! I migrated that article over to my personal domain BTW http://www.boyter.org/decoding-captchas/ It is 100% the same though. I wanted to shut down some of the redundant domains I had lying around.