Add features from original XSD tool and better PCL support

[fubar-coder]

• Use Mono.Options
• Integrate Mono.Options with Costura (Fody module) to still have only one executable
• Add compatibility command line arguments /out, /c, /nologo
• Implement /order to get a stable XML element order when serializing an object
• Implement /edb to add an INotifyPropertyChanged implementation to types
• New /pcl argument to remove attributes unsupported by PCLs (e.g. Serializable)
• Enhanced /combine argument to (optionally) accept an output file name
• Implement /l and /language with value CS or VB

[mstijak]

I never expected that someone is actually using xsd2. I enjoyed reviewing your PR. Thank you!

Do you want me to publish a new NuGet package?

[fubar-coder]

No, there is no need to publish a new NuGet package. BTW: This project is exactly what I was looking for, having the same code generation but with some additional features 😃