Results where the housenumber was dropped are an unlikely result
when they refer to something other than a street. Therefore
increase their result rank so that other matches are tried first
before choosing them as a result.
Improves #2167.
So far the data directory constant has pointed to the source
directory to be usable with different subdirectories. Now only
the data subdirectory itself is being used with the constant,
so point to the directory directly.
This replaces {data_dir}/settings throughout the code, so that
the configuration may be placed somewhere else in the directory
structure (e.g. in /etc).
