M core/access_api.php
(access_can_close): Reversed the login to make it less confusing.

M core/html_api.php

• Moved the td's inside the html APIs so that they are only printed if the button is
  printed. This removes spaces between buttons that were dependent on the number of hidden
  buttons (which doesn't make sense). I didn't want to put the td's in the html_button
  since it is a generic method.

M bug_view_advanced_page.php
M bug_view_page.php

• Simplified the code.
• Now the buttons always appear centered independent of the hidden buttons.
• More checks can still move to the APIs (can be done later).

git-svn-id: http://mantisbt.svn.sourceforge.net/svnroot/mantisbt/trunk@1834 <a class="text" href="/?p=mantisbt.git;a=object;h=f5dc347c">f5dc347c</a>-c33d-0410-90a0-b07cc1902cb9