examples/calculator: updated to latest gtk module specification

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/gtk: renamed to gtk3_4

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/gtk: adds gtk3_6 and move GtkSearchEntry to it

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/gtk: brings back the gtk lib as a defaut redirection

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
lib/gtk: clean up trailing white spaces

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>