basic map of planet support

- modify continent determination to only give out africa and asia (map
of planet uses these togeher on the same continent)
- modify dictionaries to only have grassland, plains, desert, and the
only features are jungle and marsh. marsh can occur on a hill, jungle
and marsh only occurs in grassland
- place silver (minerals) and spices (kelp) in the ocean
make icons (not implement)
centauri map labels
put icon in readme
icon?
icon??
icon???
adjust centauri metrics
saturate icons
adjust centauri terrain

prevent ocean ice from interfering with centauri coasts
only one centauri subpolygon label per polygon
label centauri wonders
version 6 release
Merge pull request #1 from zoggop/testing

merge Testing into master