New client layout

With release 0.0.5 the client architecture is refactored.
A new layer is introduced to encapsulate xml-rpc calls into a library, so that front-ends only implements controls and views and business logic is driven by centralized libs.
This is useful for the PHP language, since we yet have two front-ends (CLI and GTK) that uses the library; for the Java Client a library can be done too, but I actually suspended the development of Java front-end (if anyone want to proceed is welcome!)