Added file_exists check before deleting session file in destroy() of VuFind/Session/File.php to prevent Warning: unlink(): No such file or directory

Prevent adding a module if it's already in the list.
Because on some systems it's not possible to define environment variables, you should be able to add the module to the normal module list (defined at the top of this file). Problem occures when you work with different systems for dev/test/prod etc. and want to share the same code base.

For the Aleph Driver, it's possible that the item ID (id from route) and the holding ID (id from query) are different. With the += operator for merging, the id attribute from $keyValueArray was not used and an invalid REST url was sent to the ILS.
I'm not sure why the record id is loaded from the route here. With this fix, it's only used as a fallback when not defined in the query as a HMACKeys-variable of the ILS.

Aleph uses id:item_id which causes the conflict here.

This might deserve its own class if it ever needs to be reused in the future.

Note: this will create some inefficiency until \VuFind\Config\Reader is factored out of code; in some cases, configurations will load twice.  Should be sorted out soon.