Implement psr4

[valentintorikian]

I've implemented the composer's PSR-4 and fixed a bug with the -r options

• The directory structure is pretty different, but I think that it convey your initial intentions pretty well
• The tool is now started through bin/mar.php, this way we avoid the definition + initialization of the class in the same file, options are unchanged

[valentintorikian]

Brainfart on the -r option, will reopen