Change keybindings to suit my environment

(Alt bindings conflict with dwm)
Temp fix for off by one error.

Note from the Lua manual for string.byte and string.char:

"Note that numerical codes are not necessarily portable across
platforms."

The original worked fine for me on OSX PPC, but on i386 NetBSD it's off
by one. Could do with a better fix (I.e understanding it, rather than
just sticking in the -1)