feat(tischcontroller): show the current time and table
feat(tischcontroller): allow the master to set the time
feat(buttons): pack the structs and reduce their size
feat(time): subtract method and const arguments
feat(buttons): pin definitons for on-board buttons
fix(lcd): correct orientation
fix(serial): reduced the buffer size
fix(packet): check the crc of the packets
feat(time): functions to start and stop the time
fix(uart): reduced buffer sizes
feat(bus): add broadcast address
feat(bus): zero packet data
feat(master): main state machine
fix(display): refresh display every .5 s
fix(terminal): redraw complete content
fix(control): add missing include
feat(debug): add some functions to debug over the serial line