Use VIS_CSTYLE for the arguments and add the missing escapes it can

generate to the parser.

cmd-parse.y

@@ -1118,9 +1118,24 @@ yylex_token_escape(char **buf, size_t *len)
 	switch (ch) {
 	case EOF:
 		return (0);
+	case 'a':
+		ch = '\a';
+		break;
+	case 'b':
+		ch = '\b';
+		break;
 	case 'e':
 		ch = '\033';
 		break;
+	case 'f':
+		ch = '\f';
+		break;
+	case 's':
+		ch = ' ';
+		break;
+	case 'v':
+		ch = '\v';
+		break;
 	case 'r':
 		ch = '\r';
 		break;