title: Pasting tables to spreadJS without losing the formatting
body: <p>I have been trying to paste a table from my tinyMCE text editor to SpreadJS. 
  I am using a custom made clipboard instead of the default one for this operation, and on copy, table values(text, html) from tinyMCE are successfully passed to the SpreadJS clipboard as well. but as i try to paste it in SpreadJS only the text is appearing in cells. Is there any way i can get this done ? below is the custom paste function which I am using.</p>
  
  <pre><code>spread.commandManager().register('custompastefunction', {
                    canUndo: true,
                    execute: (context, options, isUndo) =&gt; {
                       //setting the contents copied from tinymce to spreadJS clipboard here.
                       designer.actions.doAction("paste", spread, 0 /* All */);
                       }                     
                    }
                 });
  </code></pre>