Add Quenya ⟨hl⟩ and Sindarin ⟨lh⟩

Both represent a “voiceless L”; Appendix E of The Lord of the Rings
notes that the Quenya ⟨hl⟩ was pronounced like /l/ by the Third Age, but
for now we reproduce the original pronunciation. (Maybe we can later use
conditional rules for different pronunciations, but I think for now I
won’t go down that road.)

dictsource/sjn_rules

@@ -84,7 +84,7 @@
 
 .group l
 	l	l
-	// TODO lh
+	lh	l#
 
 .group m
 	m	m