add minimap information layer for traffic jam

[Sigra]

Add a minimap information layer for traffic jams (suggested by Tibor at [http://wl.widelands.org/forum/topic/42/]). This could be done by making the pixel red if the map node has a flag with at least 4 wares waiting. It is also worth considering to make the pixel redder the more wares are waiting at the flag. (To be implemented in calc_minimap_color, render.cc.)

[SirVer (sirver)]

work on this can start. It shouldn't be too hard to do.

[Jens Beyer (qcumber-some)]

I checked this, the implementation itself was not too hard. But the suggestion to make a red pixel where a flag has more than x wares is a bit unimpressive. First, it does not blend too well with a red player color. Second, on Winterland there are already orange pixels for normal flags in the flags layer (remember, on opening the window, all layers are active). Third, a single red pixel is not very visible on the terrain layer.

I guess we should find something else. Maybe a message from win conditions or exhausted mines?

[Jens Beyer (qcumber-some)]

Sometimes I wished the comments could be edited...

Last sentence should be:

"I guess we should find something else. Maybe a message like from win conditions or exhausted mines?"

[SirVer (sirver)]

Setting to incomplete for bug sweeping.

[Launchpad Janitor (janitor)]

[Expired for widelands because there has been no activity for 60 days.]

[GunChleoc (gunchleoc)]

Migrated to https://github.com/widelands/widelands/issues/1781