Merge branch 'feat/datetime'
src: user: Extract toggle time into constant
src: user: Change USER_VISUAL_INDICATION_TOGGLE_MS to 200
src: uart: uart_puts_p(): Use PGM_P as type for argument
src: uart_protocol.c: uart_protocol_tokenize_command_buffer(): Change type of arg
src: uart_protocol.c: uart_protocol_tokenize_command_buffer(): Rename arg to argc
src: uart_protocol.c: uart_protocol_tokenize_command_buffer(): Remove empty line
src: uart.h:  uart_flush_output(): Add todo item
Merge branch 'master' into feat/log