Return false from event handler.
Use different overpass turbo call when numbers of objects is small.

When there aren't too many objects with a given key or tag, use the new wizard
interface of overpass turbo, which runs automatically in global context and
automatically zooms to the results. This is much nicer and easier.
If there are too many objects, we keep the old behaviour. Unfortunately this
is rather confusing. Maybe we can figure out something better...
Use pair of strings instead of concatenated string for hash map.

For the geodistribution hash we concatenated the key and value with an equal
sign in between and used that as a hash key. But this will lead to problems
when the key or value contain an equals sign. So instead we do the proper
thing now and use a std::pair<const char*, const char*>.
Removed TAGSTATS_COUNT_USERS.

This preprocessor macro decided whether we wanted to count the different users
using a key. This is now always on.
Removed TAGSTATS_COUNT_KEY_COMBINATIONS.

This preprocessor macro decided whether we wanted to count combinations
of tag keys. This is now always on.
Clean up output of sizes of important data structures.
Removed TAGSTATS_COUNT_TAG_COMBINATIONS.

This preprocessor macro decided whether we wanted to count combinations
of tags. This is now always on.
Cleanup of option parsing code.
Use prefix ++ instead of postfix ++.