Add ol.coordinate.format function

Return a formatted coordinate. Example usage:
  > ol.coordinate.format([0.01 ,12.14], "{x}, {y}", 2)
  "0.01, 12.14"
  > ol.coordinate.format([0.01 ,12.14], "lat: {y} / lon: {x}", 1)
  "lat: 12.1 / lon: 0.0"
Remove opt_precision check in ol.coordinate.format

Default is already 0, see http://www.ecma-international.org/ecma-262/5.1/#sec-15.7.4.5
Better ol.coordinate.* documentation
Fix `@todo observable` name reference.
Remove unnecessary Get column from observables
Merge pull request #1187 from pagameba/fix-todo-observables

Fix todo observables.
Merge pull request #1185 from fredj/coord_format

Add ol.coordinate.format function
Quote values in apidoc
Fix bottom left and top right computation in moveend example
Merge pull request #1189 from fredj/apidoc

Minor apidoc updates
Merge pull request #1182 from fredj/moveend_example

Wrong extent coordinate order in moveend example