add semver as new submodule
remove unused function
use new submodule semver instead of referring to '/api' file
add local db.php file

Just copy over file from api submodule. Use site
database config. Update all require_once() calls.
merge db.php and db2.php files
undo db.php change for login.php

As login.php refers to API-internal tables,
it must not use the site-only db.php file.
copy over searchSubArray()
add submodule for HttpException
Check for duplicate user name with API
Merge branch 'independence'

As much independence from the 'api' submodule as possible.
Only login.php still relies on it. This will be avoided as
soon as registration has been reworked. Then the submodule
can be deleted as well.