Merge pull request #314 from NICTA/cleanup

Cleanup
Fixes for CSV support.

* Fix incorrect reference to `calculateVarMinMax` in Variable.js.
* Don't set the Scale to NaN when a column has a mix of numbers and strings.
Replace Data and Map icons with text.
Add a "Legend" button when the topmost layer has a legend.

Clicking the button opens the legend URL in a separate tab.
Improve test of WebGL support.

Use the same options for WebGL context creation that Cesium itself uses.
This avoids the potential for National Maps test to succeed only for
Cesium's actual creation to fail.
Add a distance legend.
Do less DOM manipulation while updating the distance legend.
Move the distance legend below the lat/lon display.
Merge pull request #323 from NICTA/csvFixes

Fixes for CSV support.
Merge pull request #324 from NICTA/legend

Add a "Legend" button when the topmost layer has a legend.
Merge pull request #325 from NICTA/matchContextCreationOptions

Improve test of WebGL support.
Merge pull request #326 from NICTA/distanceLegend

Add a distance legend
Merge branch 'master' of https://github.com/NICTA/nationalmap into region_perf
added lga's and fixed bugs