* milena/mln/core/image/imorph/interpolated.hh: Make the vector
	type more generic.

	* milena/mln/core/point.hh: Provide specific conversion operators
	for float and double.

	* milena/mln/fun/internal/x2x_linear_impl.hh: Allow to set the
	matrix value type.

	* milena/mln/fun/x2x/composed.hh,
	* milena/mln/fun/x2x/rotation.hh,
	* milena/mln/fun/x2x/translation.hh: Introduce data_t typedef
	passed to x2x_linear_impl.