Add flight animation example

[tsauerwein]

One more example demonstrating the use of postcompose.

http://tsauerwein.github.io/ol3/animation-flights/examples/flight-animation.html

[elemoine]

The build fails:

info ol Parsing dependencies

info ol Compiling 358 sources

ERR! compile /home/travis/build/openlayers/ol3/build/compiled-examples/all.js:2207: ERROR - 'arc.GreatCircle' used but not goog.require'd

ERR! compile         var arcGenerator = new arc.GreatCircle(

ERR! compile                            ^

ERR! compile 

ERR! compile 

ERR! compile 1 error(s), 0 warning(s)

ERR! compile 

ERR! Process exited with non-zero status, see log for more detail: 1 

make: *** [build/compiled-examples/all.combined.js] Error 1

which makes sense as we don't have externs for the arc library.

Two options: (a) create an externs file for the arc library, (b) add // NOCOMPILE as the first line of the flight-animation.js file.

+1 for option (a).

[tschaub]

@tsauerwein can you update this with // NOCOMPILE? Having externs files for things only used in the examples seems like overkill to me. But I know we already do this.

[tsauerwein]

Thanks for the reminder, I rebased and added NOCOMPILE.

[tsauerwein]

I will update the example once #4401 is merged.

[tsauerwein]

PR updated, a review would be appreciated! :)

[fredj]

LGTM

[tschaub]

Instead of having people mutate the frame state, I think we should encourage the use of map.render() (this is part of the documented API).

[tsauerwein]

Thanks for the feedback, merging.