[Fix #433] Disable problematic binding M-[
Simplify sexp wrapping code
Add wrapping commands to ielm-map
Improve tab's behavior

It now does both indentation and completion (when supported)
Minor change
Merge remote-tracking branch 'prelude/master'

* prelude/master:
  Improve tab's behavior
  Add wrapping commands to ielm-map
  Simplify sexp wrapping code
  [Fix #433] Disable problematic binding M-[