Add nan to lib9. Fix memory corruption bugs in 9term.

B - fixed usage, DISPLAY :0 vs :0.0 9term - fixed various terminal things rc - notice traps in Read _p9dir - only run disk code for disks dirread - getdirentries on FreeBSD and Linux are different w.r.t. meaning of off. notify - set up so signals interrupt system calls bprint - use bfmt.

Updated for current libraries by Caerwyn Jones. Button-3 plumbing (like in acme) by rsc.