map display colormap now grayscale with colors for abnormal values.
map_display again supports alpha property
map-display: moved manual-object creation into initialization.
Added support for OccupancyGridUpdate messages.
map_display: Added color scheme property and fixed same-material-for-every-map-instance bug
Fixed bug in MapDisplay: updates were not unsubscribed properly.
Merge pull request #651 from ros-visualization/map-display-update

Map display expansion to support costmaps