add python script for recursive copy of DLL dependencies

You may be aware of a little python script that manages to parse PE header, extract DLL dependencies and copies the DLLs: https://github.com/performous/performous/blob/master/win32/mxe/copydlls.py

I think this script is very useful for shared builds with MXE to reduce deployment trouble for shared builds.

I modified it a little bit for commandline parsing and recursive dependency checking.

It's purpose is to fill a directory (targetdir) with DLLs you need to run your application.
```python copydlldeps.py -h``` yields
```
usage: copydlldeps.py [-h] -C CHECKDIRS [CHECKDIRS ...] -L LIBDIRS
                      [LIBDIRS ...]
                      targetdir

Recursive copy of DLL dependencies

positional arguments:
  targetdir             target directory where to place the DLLs

optional arguments:
  -h, --help            show this help message and exit
  -C CHECKDIRS [CHECKDIRS ...], --checkdir CHECKDIRS [CHECKDIRS ...]
                        directories whose depencies must be fulfilled. All PE
                        files will be checked (mostly .exe and .dll files)
  -L LIBDIRS [LIBDIRS ...], --libdir LIBDIRS [LIBDIRS ...]
                        include directories to search for DLL dependencies
                        (only .dll files will be used from here)
```