GNSS improvments: - Introduce alive indicator; Status string will switch between white and grey with every message received from the module - shorten visibility of "shutting down" string. a busy wait of 1 second was applied in the sleep prepare function. The time is now included in the time needed to prepare the module for low power operation - make sure GPIO is properly initialized after deep sleep

checksum_final_add_fletcher.exe OSTC4_firmware_upload.bin OSTC4_FONT_upload.bin OSTC4_RTE_upload.bin