Measure API enhancements

This pull requests suggests to change Measure.js so that:

1. `displaySystem` & `geodesic` properties get promoted to API properties
2. The documentation for `measureImmediate` contains all parameters
3. removes dangling whitespace

The points 2. and 3. are trivial. 1. is non-trivial, but makes sense, since `geodesic` is used in the official examples as API property and `displaySystem` is the easiest way for users to configure the measure output.

Please review.