Implement beginnings of Touchscreen4D.
touchscreen4d: Setup UART when initializing.
touchscreen4d: Implement clearing the screen.
touchscreen4d: Implement changing baud rate.
touchscreen4d: Make draw_char() draw in white by default.
touchscreen4d: Oops, set_baud() should return a value.
touchscreen4d: Document color format.
touchscreen4d: Implement touch-related display controls.
touchscreen4d: Implement pen size.
touchscreen4d: Rename get_touch_activity() to get_touch_status().
touchscreen4d: Rename enable_touchscreen() to toggle_touchscreen() and change functionality accordingly.
touchscreen4d: Implement two touch related functions.
touchscreen4d: Add an example program.
touchscreen4d: Don't use the yaal::internal namespace.
touchscreen4d: Move the helper types to the top.
touchscreen4d: Make the initial baudrate a template parameter.
touchscreen4d: Make init() set a new baudrate after the initial one.
touchscreen4d: Use a more descriptive name for the serial connection template parameter.
touchscreen4d: Remove an unneeded enum keyword.
touchscreen4d: Remove an unnecessary static_cast.