Component for color overlays

**Needs fife git** to work, but has no problems running without (will just not show anything).

Was developed in #2119 largely and then split out for lack of proper test images to get that one merged.

Color overlays
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[link to pwetty overlaid ship pic!] (http://up.unknown-horizons.org/f/?id=560&n=2013-11-23.23-24-48.750031.png)

[Base image] (../blob/overlays/content/gfx/buildings/pioneers/tower_wooden/as_woodentower0/idle/225/0.png) + [image defining colored area(s)] (../blob/overlays/content/gfx/buildings/pioneers/tower_wooden/as_woodentower0/color_idle/225/0.png) + color (bordeaux-ish) = [overlay tower] (http://up.unknown-horizons.org/f/?a=v&id=474&n=2013_4-tower-overlay.png)

Supposed to be used for e.g. ships with flags in player color, ornaments at main square, ground units, etc.