Make 'geodesic' & 'displaySystem' API properties.

The geodesic-property is used inside of our examples, yet isn't officially
part of the public API.

The displaySystem-property provides a very useful way of configuring the
output of the measurements and should be promoted as well.
Adjust method documentation.
Remove end-of-line whitespace.
Promote several properties to public API.

The properties

  * layers
  * queryVisible
  * url
  * layerUrls
  * infoFormat
  * vendorParams
  * format
  * formatOptions

should all be visible in the public API since they are essentially very
convenient to use when customizing the control.
Reformat documentation to match surrounding doc.
Readd dangling space in header.

This allows for easier search and replace operations. The space will
eventually be removed in all files in a seperate commit.
Merge pull request #871 from marcjansen/measure-api

Measure API enhancements
Remove end-of-line whitespace.

The license header is left untouched, to keep it the same in all files.
A seperate commit will probably deal with this
Merge pull request #872 from marcjansen/wmsgfi-api

WMSGetFeatureInfo API enhancements