Modularization

[Degubi]

Add a module-info.java file to the source directory for the Java 9 module system.
I don't know which java version this library requires, but adding this file will require at least Java 9.
We need this module file, because without it it's very hard to create jlink images with this library.
The file should look something like this:

module shellinks {
    exports mslinks;
    exports io;
    exports mslinks.data;
    exports mslinks.extra;
}

• This defines that the module name for the jar should be: "shellinks" (can change)
• This means that all packages are exported (no encapsulation on package level).

I can create a PR for this if this is fine.

[DmitriiShamrikov]

Please create the PR. But please name the module the same way (mslinks)