[BUG][PLAYER/STYLES] Silhouette style objects / lemmings invisible in C.P. Mode

[namida]

(CP Mode = Clear Physics Mode)

Clear physics mode defaults to a black background. However, the objects and lemmings in the Silhouette style are pure black, meaning they become invisible (aside from trigger areas / positioning dots, where applicable) in clear physics mode. Terrain is fine, because it changes to the checkerboard grey.

Lemmings could perhaps be fixed by always using the default sprites in clear physics mode. Though this would require a bit of revision of the code to always keep the default sprites in memory in addition to any custom ones, and switch between them when using clear physics mode.

Objects could perhaps have a flag added to their metainfo, that if active, inverts the object's colors in clear physics mode. This would resolve the issue, but would rely on honesty (and more significantly, awareness) by any style designers.

An alternative option could be to, similar to what's done with terrain and trigger areas, ignore the normal colors and draw objects / lemmings in a single fixed color when in clear physics mode. This way they could even combine colors with other important details.

I don't think "rely on people not to do this" is a valid approach here, because the Silhouette style was - as far as I know - not created with the intention of making clear physics mode difficult to use, but simply with the intention of producing a neat artistic effect (which it does very well IMO). Furthermore, an approach like the ones above both prevent intentional abuse and deal with any cases where this happens as an unintended side effect, as well as perhaps helping with a few less-clear cases even in "normal" styles.

[IchoTolot]

It also would have the neat side effect that lemmings with permanent skills would appear with their blue hair again in clear physics mode.

I am in favor of this.  

[namida]

Standard sprites would be quite a lot of work, but I've implemented code (commit d133204) to draw lemmings and objects in a single, solid color - red for objects, blue for regular lemmings, green for lemmings with permanent skills. The selected lemming will get a reddish tinge, while zombies get drawn darker than regular lemmings.