Integrating widget help

Backsides of widgets have a button that displays help. Still need button
to remove the help frame.
Changed error handling of no data transfer in drop

If debugging just logs it rather than alerting. Also log message
distinguishes from no data transfer and unable to make sense of the
JSON.
Improved appearance of widget help button

Looks like tourist information now and located better.
Added a file for testing.
Widget help fully operational
Sensor help buttons style changed

To fit together with widget help buttons.
Element attribute help buttons style changed

To match others.
Added documentation of boxes
Added image prefetching to the manual's index page.
Add scales documentation

And updated boxes documentation.
Fixed boxes in index pages

They were running which interfered with opening backside.
Also pages refers to manual with URL parameter reset=1
Plain text element widgets put z-index in JSON

Which threw off scales in comparing text.
Added documentation for widget elements

And updated scales documentation.
Updated compiled version
Merge pull request #164 from ToonTalk/master

Updating gh-pages to master