Bug 22168: Improve styling of new chart settings for reports

Bug 22168: Improve styling of new chart settings for reports

This patch updates a number of aspects of the reports chart creation
interface: Chart creation form is now shown in a modal window, and a
separate link has been added to show or hide the chart itself.

Also changed: Minor markup and JavaScript cleanup.

To test, apply the patch and go to Reports -> Saved reports.

- Run a report which returns more than one column.
- On the report results page, click the "Create chart" button. The chart
  settings form should appear in a modal window.
- Confirm that the form controls work correctly: Each label should give
  focus to the correct input. Changing the chart type should show or
  hide the appropriate form fields.
- Click the "Draw" button. The modal should disappear and the chart
  should be shown.
- Above the chart should be a "Hide chart" link which works to hide (and
  then show) the chart.

Signed-off-by: Pierre-Marc Thibault <pierre-marc.thibault@inLibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>