Add function 'proj4js_load_definition_js_settings' to return only the JS in an array, so it can be embedded in a #attached array.

Follow up on #1940410, OpenLayers JS file is calling: ...if (Drupal.behaviors.proj4js) {... it means that the behavior file needs to be loaded too.
This patch add the file to the library.

Loads projections via settings again but avoids duplicating definitions and notes on behaviour loading.
issue #1940410

(To be discussed in #1940410 if this commit and ca00b422 should be kept)

Building inline JavaScript instead of using Drupal's JavaScript settings. This is because there is no guarantee of iteration order in JavaScript objects and thus no way to ensure projections are defined before being used with the previous approach.
Loading projections as JS_LIBRARY with weight=0 so that they are present before consumers.

Automatic version detection.