feat: use m and ~ like classic vim

lib/jupyter/actions.js

@@ -381,6 +381,34 @@ define([
         );
       }
     }, 'extend-selection-below', 'vim-binding');
+
+    var cell_marker = {};
+
+    actions.register({
+      'handler': function(env, event) {
+        env.notebook.keyboard_manager.enabled = false;
+        document.addEventListener('keydown', function (event) {
+          var key = event.key;
+          var idx = env.notebook.get_selected_index();
+          cell_marker[key] = idx;
+          env.notebook.keyboard_manager.enabled = true;
+        }, { once: true });
+      }
+    }, 'mark-cell', 'vim-binding-normal');
+
+    actions.register({
+      'handler': function(env, event) {
+        env.notebook.keyboard_manager.enabled = false;
+        document.addEventListener('keydown', function (event) {
+          var key = event.key, idx;
+          if ((idx = cell_marker[key]) == null) return;
+          env.notebook.select(idx);
+          env.notebook.get_cell(idx).focus_cell();
+          env.notebook.scroll_cell_percent(idx, 0, 0);
+          env.notebook.keyboard_manager.enabled = true;
+        }, { once: true });
+      }
+    }, 'goto-mark-cell', 'vim-binding-normal');
   };
 
   exports.detach = function() {

lib/jupyter/shortcuts.js

@@ -75,6 +75,8 @@ define([
       'shift-l': 'jupyter-notebook:toggle-cell-line-numbers',
       'shift-v': 'jupyter-notebook:toggle-cell-output-collapsed',
       'shift-s': 'jupyter-notebook:toggle-cell-output-scrolled',
+      'm': 'vim-binding-normal:mark-cell',
+      '~': 'vim-binding-normal:goto-mark-cell',
       // Defined in searchandreplace.js
       // https://github.com/jupyter/notebook/blob/4.x/notebook/static/notebook/js/searchandreplace.js#L375
       '/': 'jupyter-notebook:find-and-replace'