library version and not rely on .so being present.

allowing for much cleaner code (at the expense of an extra dependency).

+ Renamed the dlls so that the C# versions do not have the same name
      as the C DLLs on Win32. It's now "cucul-sharp.dll", mimicking GTK#.
    + Renamed namespaces: "using Cucul" instead of "using libCucul".
    + Renamed the Cucul class into CuculCanvas to avoid namespace/class
      name collisions.
    + Renamed old-fashioned "kk"/"qq" names into "dp"/"cv".