title: Issue w/ period symbol in ag-grid pressed on numpad in IE
body: <p>I am using ag-grid in my angular project. 
  The main idea is to make table editable w/ numeric values. If user presses any number or period/minus keys the cell should become editable.
  There is a problem w/ IE and numpad period key. When NumLock is on period key at numpad is not working. It seems like IE doesn't catch that the key was pressed. I have never got into this code:</p>
  
  <pre><code>this.eInput.addEventListener('keypress', function (event) {
  </code></pre>
  
  <p>It works well in Chrome. Also period key at main part of keyboard works well both in IE, Chrome.
  The same issue exists in example on ag-grid Cell Editors doc page - <a href="https://www.ag-grid.com/javascript-grid-cell-editor/#cell-editing-example" rel="nofollow noreferrer">https://www.ag-grid.com/javascript-grid-cell-editor/#cell-editing-example</a> .</p>
  
  <p>Any way to solve this?</p>