ENH: add support for CHAR_DATA token

- allows construction of string tokens holding character content.
  For example, data that has been serialized and buffered and that
  now needs to be written or sent to another process.

src/OpenFOAM/db/IOstreams/Pstreams/UIPstreamBase.C

@@ -374,6 +374,7 @@ Foam::Istream& Foam::UIPstreamBase::read(token& t)
         case token::tokenType::EXPRESSION :
         case token::tokenType::VARIABLE :
         case token::tokenType::VERBATIM :
+        case token::tokenType::CHAR_DATA :
         {
             string val;
             if (readString(val))