bring down below 102 columns
clarify the surrogate docs a little
add missing acks
fix scheme-mode and racket-mode string constants
adjust racket mode to restore the wordbreak map when it is removed
add basic support for #lang line-specific editing

Specifically, the #lang line now selects for a
definitions text surrogate, on top of which several
extensions can be built to, say, more easily add keybindings
or change indenting decisions, etc.