Many special keys don't work on OSX

[cjdshaw]

On Mac OSX (currently using 10.14.6), many special keys don't work, including
backspace - comes out as \x7f
delete - comes out as \x1b5b33 followed by \x7e
escape - ignored until a 2nd key is pressed, then they're delivered together
page-up, page-down, home, end - used as Terminal shortcuts

The terminal shortcuts can be ignored, but it would be good to have support for the others