graphics: give airport and power plants reddish border

it was yellow. The reddish border makes them look less like
IND zones.
graphics: give stadium a reddish border

reddish borders will be used for all "municipal" zones
graphics: give police station a reddish border

reddish borders are to represent "municipal" zones
graphics: give power plants a red border

red border is for "municipal" zones
tile-names: remember PWRBIT when loading tiles from save-file