Add and export View2D.calculateExtent
Use xmleql in the KML tests

This also involves some modifications to the xmleql functionality now that
it was tested with a real-life case (KML). Also, some of the input KML files
needed to be changed since we currently cannot roundtrip 100% of the input.
Asynchronous API for map#getFeatureInfo

This change allows us to use feature info services on the
server. It will also be useful for the GetFeature control to
get results from a WFS.
map#getFeatureInfo does not return anything

Thanks @elemoine for catching this.
Export and externalize Control.setMap
Create ol.inherits alias, and export it
Add a custom controls example

Inspired from @cedricmoullet's ZoomExtent example in https://github.com/cedricmoullet/ol3/commit/3312c37ed0ac93e9b3c2cb0cea76a070ea1c2cf4.
Export Control.getMap
Externalize Control.handleMapPostrender
Use our own null function for handleMapPostrender

If we use ol.control.Control.prototype.handleMapPostrender = goog.nullFunction the API doc doesn't show the mapEvent parameter of the handleMapPostRender function.
Merge pull request #703 from ahocevar/getfeatureinfo-async

Asynchronous API for map#getFeatureInfo. r=@elemoine
Merge pull request #699 from bartvde/kmlxmleql3

Use xmleql in the KML tests (r=@ahocevar)
Merge pull request #700 from elemoine/calculate-extent

Add and export View2D.calculateExtent
Merge pull request #706 from elemoine/user-extensions

Custom control framework
handleMapPostrender returns undefined

Without this we get the following warning from the compiler:

JSC_EXPORTED_FUNCTION_UNKNOWN_RETURN_TYPE. Unable to determine return type for exported function ol.control.Control.prototype.handleMapPostrender at ../src/ol/control/control.js line 79 : 51

I'm not sure why explicitely specifying the return type is required here.
GML parser.

This adds a parser (read/write) for GML v2 and v3. GML v3 is limited to the
simple features profile of GML 3.1.1, just like OpenLayers 2 was. This will
be the basis for the WFS parser, but it only makes sense to continue this work
once feature modification (insert, update, delete) is in place in ol3. So the
WFS parser will be another pull request.
incorporate review from @ahocevar
do not specify the source projection in ol.parser.ReadFeaturesOptions anymore
Merge pull request #709 from bartvde/gmlfresh

GML parser (r=@ahocevar)
Accurate hit detection

With this change, hit detection for lines and points gets very
accurate, because the vector renderer instance keeps track of
line widths and point symbol sizes. After doing a bbox query in
the RTree, returned lines and points are evaluated against the
thresholds of their line width or symbol size. The KML example
with its different symbolizers now has getFeatureInfo too to
show this in action.