Add support for folder hierarchy.

[mriesch-tum]

As there are thoughts about rewriting the whole project, I would like to add some feature requests. This way they can be already discussed and -- if desired -- they can be integrated from the very beginning of the new project. (Alternatively, of course, they can be implemented in the existing version).

Given a folder structure with many MATLAB files in it, it would be nice to have a function that applies the format in-place for each file. I think it would help the developers a lot to have such a batch formatting tool. The main application here, however, is continuous integration. In such a scenario, all files can be formatted and differences can be easily detected. This feature should include a way to exclude certain files or directories from formatting. I have some first code lying around, if desired I can make it available.

Related, but maybe a different issue: It would be nice if the script considered a given settings file in the project root (for project specific settings). Maybe the settings can be overwritten by another settings file in a subdirectory. In summary, the recursive formatting function mentioned above scans for a settings file in the current directory, in a top-level directory, and finally in the MBeautifier settings directory.