This fixes the path to source files in some unit tests and allows
to get rid of a few duplicate lines.

to allow third-party applications to link with caca-sharp, and tune a
few things here and there.

split is rendered moot by the plugin system: when enabled, binaries do
not link directly with libX11 or libGL. I hope this is a step towards
more consisteny and clarity.

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".