Ignore resize and error keys in getstring()

Partly addresses GitHub issue #145.

Suggested-by: Lars Henriksen <LarsHenriksen@get2net.dk>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/getstring.c

@@ -259,6 +259,9 @@ enum getstr getstring(WINDOW * win, char *str, int l, int x, int y)
 		case CTRL('G'):
 			return GETSTRING_ESC;
 			break;
+		case ERR:
+		case KEY_RESIZE:
+			continue;
 		default:	/* insert one character */
 			c[0] = ch;
 			for (k = 1;