Minor cleanups.
Absorb padding into border. Draw scrollbar on outside, full height.
Remove debug stuff from read() loop in terminal.
Some renames in Buffer to accommodate scrolling (Buffer2).
Buffer2 WIP of scrollback.
We only translate ASCII chars in Terminal::translate().
s/\<len\>/length/g and always qualify utf8::Length.
Checkpoint in scrollbar work. About to remove old Buffer class.
Renamed Buffer2 -> Buffer, clobbering the old one.