1. in tos_at.h, added int fuzzy_matching; field into at_echo_st struct, if this field is set to K_TRUE, then if echo message contains the string in "echo_expect" field.
2. added __API__ int tos_at_echo_fuzzy_matching_create(at_echo_t *echo, char *buffer, size_t buffer_size, char *echo_expect_contains) api to tos_at.c, which will create an at_echo_t with fuzzy_matching = K_TRUE;
3. added RHF76_ATCMD_SET_DELAY and rhf76_set_delay to RHF76.h to allow set/query RX delay config
4. added RHF76_ATCMD_SET_DATA_RATE and rhf76_set_data_rate to RHF76.h to allow set/query date rate config
5. added rhf76_at_cmd_exe for DEBUG purpose, so that user can execute any AT+ commands they want
6. added code in lora_demo.c to demonstrate package segmentation.
1. added AT+ command "AT+MSGHEX" and change previous RHF76_ATCMD_FMT_SEND_MSGHEX to RHF76_ATCMD_FMT_SEND_CMSGHEX
2. implement send_unconfirmed with a non-breaking approach: added int (*send_unconfirmed)(const void *buf, size_t len); event handle in lora_module_st; added int tos_lora_module_send_unconfirmed(const void *buf, size_t len); in lora_module_wrapper.c; and implement static int rhf76_send_unconfirmed(const void *buf, size_t len) in RHF76.c
3. added { "+MSGHEX: PORT:", rhf76_incoming_data_process } in event array rhf76_at_event so that the device is able to process the downlink data when it is configurated to send unconfirmed message.
4. added AT+ command "AT+REPT", and implement the static int rhf76_set_repeat(uint8_t num) to enable user to set repeat times (1-15) while using "unconfirmed message"
5. updated the instructions of implemeting up-link parser and downlink parser on the server in the file "..\board\NUCLEO_STM32L073RZ\BSP\Src\lora_demo.c"
