[REQ] improve php-dt naming of collections

[lingonl]

The php-dt generator creates Collection objects with generated unique names. See: PhpDataTransferClientCodegen.java#L435

This will yield a lot of CollectionXX classes, including uniquely named ones that have the exact same purpose/contents.

Would it be possible to change the schema name to just use the type of the items in the container? That way the generated code could have collections like "StringCollection", "UserCollection" or any other "ModelCollection".