Small additions to dashboard (and tweaks)

* Added title (mouse-over) and alt text to forecast images.
* Added first pass of api reference document for ExternalWeather.php
showing sample results (they are ugly!) of the forecast.
* Made vertical space for present conditions a little taller.
* Added title (mouse-over) and alt text to present conditions images.
* Added CSS to fix tab spacing issue in Chrome (ugh, browser specific
code).