introduce clientpool, rename builder namespace to client
add solr clients to the client-pool
pass solr-clients to the pool
introduce and use index-name parameter
cleanup client/endpoint configuration
use solarium build in endpoints to handle multiple cores
use solarium build in endpoints to handle multiple cores
introduce indexHandler property to handle a suitable core for the entity
bringt the green light back
add tests for multicore handling
add tests for index property
add documentation for index feature
add phpdocs