The token string is only required by the PartialToken type, so
it can simply save the token string internally. No need to pass
it to every type.
Also moves the check for multi-word partials to the token loader
code in the tokenizer. Multi-word partials can only happen with
the legacy tokenizer and when the database was loaded with an
older version of Nominatim. No need to keep the check for
everybody.
Full-word tokens are no longer marked by a space at the
beginning of the token. Use the new Partial token category
instead. This removes a couple of special casing, we don't
really need.
The word table still has the space for compatibility reasons,
so the tokenizer code needs to get rid of it when loading the
tokens.
This adds an installation step for PHP code for the tokenizer. The
PHP code is split in two parts. The updateable code is found in
lib-php. The tokenizer installs an additional script in the
project directory which then includes the code from lib-php and
defines all settings that are static to the database. The website
code then always includes the PHP from the project directory.
