added feature to guess the compression configuration

• if samples = 0 the cmp_tool counts the samples in the data file and uses them
• if buffer_length = 0 the 2*samples parameter is used as buffer_length
• added feature to guess the compression configuration
• some code refactoring
• added more detailed error messages
• small bug fixes

include/cmp_guess.h

+/**
+ * @file   cmp_guess.h
+ * @author Dominik Loidolt (dominik.loidolt@univie.ac.at),
+ * @date   2020
+ *
+ * @copyright GPLv2
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * @brief helps the user to find a good compression parameters for a given
+ *	dataset
+ */
+
+#ifndef CMP_GUESS_H
+#define CMP_GUESS_H
+
+#include "cmp_support.h"
+
+#define DEFAULT_GUESS_LEVEL 2
+
+#define CMP_GUESS_DEF_MODE_DIFF		MODE_DIFF_ZERO
+#define CMP_GUESS_DEF_MODE_MODEL	MODE_MODEL_MULTI
+
+/* how often the model is updated before it is reset default value */
+#define CMP_GUESS_N_MODEL_UPDATE_DEF	8
+
+uint32_t cmp_guess(struct cmp_cfg *cfg, int level);
+void cmp_guess_set_model_updates(int n_model_updates);
+
+uint16_t cmp_guess_model_value(int n_model_updates);
+
+#endif /* CMP_GUESS_H */