Move buffers around instead of copying them.
Fix construction of objects in buffers.
Remove unused debug option.
Clean up reliable_read function.
Simplify and speed up PBF reading.
Renamed osmium::index::map::Base class to Map.

"Base" was a bad class name, it is too generic and only made sense in
combination with the namespace.
Add missing include.
Add Dummy and StdMap index map implementations.

And some general cleanup of index map classes.
Index map updates.

Index map key is now a template parameter for all implementations. If an entry
is not found all implementations throw out_of_range now. Also there are some
tests now checking these things.
Rename CoordinatesForWays handler into NodeLocationsForWays