simplified error formatting in qse_awk_t

- added qse_awk_errstr_t and related functions
- changed the Awk class
also fixed a minor bug in qse_awk_rtx_call()

qse/lib/awk/err.h

@@ -0,0 +1,33 @@
+/*
+ * $Id: misc.h 135 2009-05-15 13:31:43Z baconevi $
+ *
+   Copyright 2006-2009 Chung, Hyung-Hwan.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+ */
+
+#ifndef _QSE_LIB_AWK_ERR_H_
+#define _QSE_LIB_AWK_ERR_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+const qse_char_t* qse_awk_dflerrstr (qse_awk_t* awk, qse_awk_errnum_t errnum);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+