Should default to building the library, not getsubfont.o.

If $font is not set, the default font is constructed from font data linked into every libdraw binary. That process was different from the usual openfont code, and so it was not hidpi-aware, resulting in very tiny fonts out of the box on hidpi systems, until users set $font. Fix this by using openfont to construct the default font, by recognizing the name *default* when looking for font and subfont file contents. Then all the hidpi scaling applies automatically. As a side effect, the concept of a 'default subfont' is gone, as are display->defaultsubfont, getdefont, and memgetdefont.

Also add setcursor2, esetcursor2, and draw protocol encoding. Calls to the old setcursor, esetcursor create a 32x32 by pixel doubling when needed.

don't set PLAN9 don't set PLAN9

which were completely bogus. (Libthread used to ignore them but not anymore. Maybe we really should ignore them, but that breaks Venti, which needs *really* big stacks.)

Turn window destruction into "hangup" note. Fix (?) snarf buffer management. Add latin1 keyboard translation.