termcurses: Only set new color if necessary.

Previously we emitted color escapes for _every_ single character. As this is
quite a waste and floods the terminal device, this should keep those escapes
down. Especially wasteful: Color CSI escapes for clearing the dirty rects.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
AnimationTest: Check for different frame sizes.

Different frame sizes might have bugs in our autogrow code, so let's add an
extensive test case. Originally I was looking for a visual output bug, but
eventually ended up only discovering non-optional ways to debug those.

Maybe let's add direct test programs for the other compilation targets, for
example by moving around nome sprites and animations which then form a pattern
where errors can be spotted visually.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>