Rewritten prototype $ for show/hide to jQuery

Resolves #873 
This is an invalid test for existence in jQuery, the correct (non-intuitive...) way is to test the return of ```.length``` per http://learn.jquery.com/using-jquery-core/faq/how-do-i-test-whether-an-element-exists/.  I think the code is more readable with the test than without it per the comment in the url above, as well as being consistent.