RPM configurable location database

[MOARdV]

This isn't fully thought out yet - but what about having a way to store / recall locations on planetary surfaces. It could be used for displaying downrange distance and straight line distance from a location, and maybe fed into MechJeb's landing AP. Instead of storing per-ship, I'd store it per-install (either in the persistent file like other mods do, or in some other file in the JSI directory - although the former is probably the better way to do it).

[Mihara]

Try a scenario module. I initially thought of using it to store all the persistence variables, but in the end decided that tracking part identifiers for part-specific data was too much work when the game already does this. For global data like that, though, a scenario module would be ideal.