shell: Shell subsystem reimplementation

New shell support features like:
- multi-instance
- command tree
- static and dynamic commands
- multiline
- help print function
- smart tab (autocompletion)
- meta-keys
- history, wildcards etc.
- generic transport (initially, uart present)

Signed-off-by: Jakub Rzeszutko <jakub.rzeszutko@nordicsemi.no>
Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>
Signed-off-by: Piotr Zięcik <piotr.ziecik@nordicsemi.no>

subsys/shell/shell_utils.h

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2018 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef SHELL_UTILS_H__
+#define SHELL_UTILS_H__
+
+#include <zephyr.h>
+#include <shell/shell.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define SHELL_MSG_SPECIFY_SUBCOMMAND	"Please specify a subcommand.\r\n"
+
+#define SHELL_DEFAULT_TERMINAL_WIDTH	(80u) /* Default PuTTY width. */
+#define SHELL_DEFAULT_TERMINAL_HEIGHT	(24u) /* Default PuTTY height. */
+
+
+
+s32_t row_span_with_buffer_offsets_get(struct shell_multiline_cons *cons,
+				       u16_t offset1,
+				       u16_t offset2);
+
+s32_t column_span_with_buffer_offsets_get(struct shell_multiline_cons *cons,
+					  u16_t offset1,
+					  u16_t offset2);
+
+void shell_multiline_data_calc(struct shell_multiline_cons *cons,
+				   u16_t buff_pos, u16_t buff_len);
+
+static inline size_t shell_strlen(const char *str)
+{
+	return str == NULL ? 0 : strlen(str);
+}
+
+char shell_make_argv(size_t *argc, char **argv, char *cmd, uint8_t max_argc);
+
+/** @brief Removes pattern and following space
+ *
+ */
+void shell_pattern_remove(char *buff, u16_t *buff_len, const char *pattern);
+
+int shell_command_add(char *buff, u16_t *buff_len,
+		      const char *new_cmd, const char *pattern);
+
+void shell_spaces_trim(char *str);
+
+/** @brief Remove white chars from beginning and end of command buffer.
+ *
+ */
+void shell_buffer_trim(char *buff, u16_t *buff_len);
+
+/* Function checks how many identical characters have two strings starting
+ * from the first character.
+ */
+u16_t shell_str_similarity_check(const char *str_a, const char *str_b);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SHELL_UTILS_H__ */