Fixed issue with some tooltips being translated twice.

http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31260

This PR fixes the issue of lstrings that have already been passed through the JText class to be translated again, on tooltips.

![icon](https://f.cloud.github.com/assets/744259/708811/f863ad68-de52-11e2-82b1-76b50a416111.png)

This has been done by adding a $translate parameter to the JHtml::tooltipText method.
To prevent the method from translating the strings, you can add a 0/false as 3rd parameter, like:
```JHtml::tooltipText(JText::_('TOOLTIP_TITLE'), $some_translated_string, 0)```

The default use is to just pass the untranslated strings to the tooltipText method, like:
```JHtml::tooltipText('TOOLTIP_TITLE', 'TOOLTIP_CONTENT')```

This PR also fixes some syntax and if statements on the disabled ordering icons in list views (that code was part of fixing the tooltips).

#### Prevent useless translation in JText::_()
It also adds a check in the JText::_() method to prevent translation of the string if it is empty or if the string starts with a '<', like for icons ```<i class="icon-menu-2"></i>```.

![icon](https://f.cloud.github.com/assets/744259/708795/4d83f5d8-de52-11e2-9584-e598237e6aef.png)

#### Testing Instructions
Switch the language debugging on and see if there are any '??' characters in any of the tooltips.
If so, report back :)