Merge pull request #3571 from damianavila/split_shortcut

Added `^M -` as shorcut to split cell.

IPython/html/static/notebook/js/notebook.js

@@ -319,6 +319,11 b' var IPython = (function (IPython) {'
                 that.undelete();
                 that.control_key_active = false;
                 return false;
+            } else if (event.which === 189 && that.control_key_active) {
+                // Split cell = -
+                that.split_cell();
+                that.control_key_active = false;
+                return false;                                               
             } else if (that.control_key_active) {
                 that.control_key_active = false;
                 return true;

IPython/html/static/notebook/js/quickhelp.js

@@ -32,6 +32,7 b' var IPython = (function (IPython) {'
             {key: 'Ctrl-m v', help: 'paste cell'},
             {key: 'Ctrl-m d', help: 'delete cell'},
             {key: 'Ctrl-m z', help: 'undo last cell deletion'},
+            {key: 'Ctrl-m -', help: 'split cell'},            
             {key: 'Ctrl-m a', help: 'insert cell above'},
             {key: 'Ctrl-m b', help: 'insert cell below'},
             {key: 'Ctrl-m o', help: 'toggle output'},