fine-grained notebook 'run' controls, closes #2521

This adds "Run All Above" and "Run All Below" menu items to Cell thanks
to @Carreau for the implementation suggestion

IPython/frontend/html/notebook/static/js/menubar.js

@@ -129,6 +129,12 b' var IPython = (function (IPython) {'
         this.element.find('#run_all_cells').click(function () {
             IPython.notebook.execute_all_cells();
         });
+        this.element.find('#run_all_cells_above').click(function () {
+            IPython.notebook.execute_cells_above();
+        });
+        this.element.find('#run_all_cells_below').click(function () {
+            IPython.notebook.execute_cells_below();
+        });
         this.element.find('#to_code').click(function () {
             IPython.notebook.to_code();
         });

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

@@ -1049,13 +1049,25 b' var IPython = (function (IPython) {'
     };
 
 
+    Notebook.prototype.execute_cells_below = function () {
+        this.execute_cell_range(this.get_selected_index(), this.ncells());
+        that.scroll_to_bottom();
+    };
+
+    Notebook.prototype.execute_cells_above = function () {
+        this.execute_cell_range(0, this.get_selected_index());
+    };
+
     Notebook.prototype.execute_all_cells = function () {
-        var ncells = this.ncells();
-        for (var i=0; i<ncells; i++) {
+        this.execute_cell_range(0, this.ncells());
+        that.scroll_to_bottom();
+    };
+
+    Notebook.prototype.execute_cell_range = function (start, end) {
+        for (var i=start; i<end; i++) {
             this.select(i);
             this.execute_selected_cell({add_new:false});
         };
-        this.scroll_to_bottom();
     };
 
     // Persistance and loading

IPython/frontend/html/notebook/templates/notebook.html

@@ -108,6 +108,8 b' data-notebook-id={{notebook_id}}'
                 <li id="run_cell"><a href="#">Run</a></li>
                 <li id="run_cell_in_place"><a href="#">Run in Place</a></li>
                 <li id="run_all_cells"><a href="#">Run All</a></li>
+                <li id="run_all_cells_above"><a href="#">Run All Above</a></li>
+                <li id="run_all_cells_below"><a href="#">Run All Below</a></li>
                 <hr/>
                 <li id="to_code"><a href="#">Code</a></li>
                 <li id="to_markdown"><a href="#">Markdown </a></li>