engine: Korean and Telex let Enter and Tab through after committing

Enter with a pending syllable committed it and stopped there, so a chat
message needed Enter twice; Korean input methods commit and pass the key
on. Japanese keeps consuming the key that confirms a reading or a chosen
candidate, as Japanese input methods do.

strans.c

@@ -698,7 +698,8 @@ transition(u32int ks, u32int mod, Str *com)
 		if(!haspre(&im))
 			return 0;
 		flush(com);
-		return 1;
+		/* Japanese confirms with the key; Korean and Telex let it on. */
+		return isjp(&im);
 	}
 	if(ks == Kback){
 		if(!haspre(&im))