added backspace functionality

sketch.js

@@ -139,6 +139,10 @@ function logKey(e) {
     case mode.insert:
       if (e.key == "Escape")
         activeMode = mode.visual;
+      else if(e.key == "Backspace"){
+        activeCell.currentChar = "";
+        activeCell = m_orientation? activeCell.neighbour[1] : activeCell.neighbour[0];
+      }
       else if (e.keyCode > 64 && e.keyCode < 91) {
         activeCell.currentChar = e.key;
         if (m_orientation) { //down

todo.md

@@ -6,5 +6,5 @@ improve input:
         ✅add replace mode (key=r)
     insert mode:
         ✅only allow characters a..z and A..Z keycode 65..90  
-        add backspacke functionality
+        ✅add backspacke functionality
         maybe arrowkeys
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