local and exporatory subdbs never created, undocumented

Neither "local" nor "exploratory" netdbs are explicitly created and their use is undocumented.

localNetDB() is never called and thus will not be created.

exploratoryNetDB() is called in a couple places and thus will be "magically" created in GetSubNetDB() ...

1. In NetDBRenderer, so only a byproduct of the console;
2. From clientNetDB(id) if id is null or "", but all calls I could find are with a non-null, non-empty id.

So it won't be created either, expect as a side effect of something on /netdb in the console

These DBs and related methods should be removed, or else fully documented and implemented. There may be some reason to separate non-floodfill exploratory tunnel usage from floodfill activity? maybe?

But this all looks like more incomplete, not fully designed and undocumented WIP. I recommend removal.