Add explicit character encoding specifications in 39 more RGL modules

To silence warnings and avoid potential problems after changing the default
encoding to UTF-8.

lib/src/romance/CommonRomance.gf

@@ -6,6 +6,7 @@
 -- which depends on [DiffRomance DiffRomance.html].
 --
 
+--# -coding=latin1
 resource CommonRomance = ParamX ** open Prelude in {
 
   flags optimize=all ;