Set boolean value to HTMLInputElement.checked

See http://www.whatwg.org/specs/web-apps/current-work/multipage/the-input-element.html#attr-input-checked
Export ol.proj.Projection#getCode
Merge pull request #1268 from fredj/export_getCode

Export ol.proj.Projection#getCode
Merge pull request #1266 from fredj/input_checked

Set boolean value to HTMLInputElement.checked
Be more strict with {Element} types
Merge pull request #1270 from fredj/element_jsdoc

Be more strict with {Element} types
Merge pull request #1267 from ahocevar/geom-clone

Deep clone geometry coordinates
Merge pull request #1265 from ahocevar/set-style

Allow to set the layer style
Adding ModifyFeature interaction

This is a first draft. The way geometry changes are handled for
now is a bit clumsy. Both updating the feature cache RTree and
making the layer aware of feature and geometry changes could be
handled in a smarter way if these changes would be made through
the layer instead of directly on the geometry or feature.
Separate add listener from method that adds index
Do not split segments while in the loop

In combination with the additional squaredDistanceToSegment
check we can ensure that a future vertex is only created on one
segment per feature, and only on the segment that it appears on.

This change also renames the misleading dragVertices_ member to
dragSegments_.
Write modifications back to the original layer

With the feature's getOriginal() and setOriginal() methods, an
undo tree can be maintained now.
Use new setCoordinates methods
Parent information no longer needed

Now that we can do setCoordinates, we no longer need to create
new geometries and assign them to a parent.
Do not create a vertexFeature with [NaN, NaN] coordinates

The RTree cannot work with NaN coordinates. So instead of
preparing a vertexFeature before we know a coordinate, we now
lazily create the vertexFeature.
Use accessor for components
Using new squaredDistanceToSegment and closestOnSegment
Updating header
Update example with more distinct colors and no social links

Conflicts:
	examples/modify-features.html
Common style for drawing and modifying