[Fix #426] Remove M-O keybinding

It caused problems in terminals.

README.md

@@ -233,7 +233,7 @@ Keybinding         | Description
 <kbd>C-c g</kbd>   | Search in Google for the thing under point (or an interactive query).
 <kbd>C-c G</kbd>   | Search in GitHub for the thing under point (or an interactive query).
 <kbd>C-c y</kbd>   | Search in YouTube for the thing under point (or an interactive query).
-<kbd>C-S-RET</kbd> or <kbd>M-O</kbd> or <kbd>Super-o</kbd> | Insert an empty line above the current line and indent it properly.
+<kbd>C-S-RET</kbd> or <kbd>Super-o</kbd> | Insert an empty line above the current line and indent it properly.
 <kbd>S-RET</kbd> or <kbd>M-o</kbd> | Insert an empty line and indent it properly (as in most IDEs).
 <kbd>C-S-up</kbd> or <kbd>M-S-up</kbd> | Move the current line or region up.
 <kbd>C-S-down</kbd> or <kbd>M-S-down</kbd>| Move the current line or region down.

core/prelude-mode.el

@@ -42,7 +42,6 @@
     ;; mimic popular IDEs binding, note that it doesn't work in a terminal session
     (define-key map [(shift return)] 'prelude-smart-open-line)
     (define-key map (kbd "M-o") 'prelude-smart-open-line)
-    (define-key map (kbd "M-O") 'prelude-smart-open-line-above)
     (define-key map [(control shift return)] 'prelude-smart-open-line-above)
     (define-key map [(control shift up)]  'move-text-up)
     (define-key map [(control shift down)]  'move-text-down)