Assign nodecomments to parent language

CivicActions is reviewing and upgrading multiple modules for use on client sites. One need that has arisen is to have all nodecomments tracked in the language of their parent comment. The following patch implements this for all node types where languages are enabled (without translation), but removing the language selection and getting the parent's language instead.

If the node type is posted in it's own right, rather than a reply, then no action is taken. If translation is enabled, then I've left this as is (since presumably some sites might want to translate comments themselves).