util_altKeyDown to allow user to choose between scrolling board and
dragging the hint rect when both are possible. add adjustYOffset;
make it and board_setYOffset more tolerant of out-of-bounds inputs and
use that to simplify calling code.
deal with the output by removing params where possible and elsewhere
by adding XP_UNUSED macro wrapping __attribute__((unused)). There
should be NO change in function in spite of the large number of files.
message is length plus data. Use non-deprecated gtk select-like
function. With these changes can play full games through the relay on
gtk. Untested on ncurses but probably broken.
