Fix #126 line number spacing not updating on zoom

This also fixes the cursor and selected line spacing not updating, which
is most obvious whet adjusting the line spacing.
Manually firing a refresh event for selectLanguage is not necessary as
it calls editor.setOption which fires this event internally.

index.js

@@ -81,12 +81,14 @@ function setSize() {
 
     document.querySelector('.CodeMirror').style.fontSize = `${size}px`;
     document.cookie = `size=${size};max-age=172800`;
+    editor.refresh();
 }
 function setSpacing() {
     var spacing = document.getElementById('spacing').value;
 
     document.querySelector('.CodeMirror').style.lineHeight = spacing;
     document.cookie = `spacing=${spacing};max-age=172800`;
+    editor.refresh();
 }
 function selectLanguage() {
     var lang = document.getElementById('select-language').value;