Pass a replay group to ol.render.Event
Make ol.FeatureOverlay use replay group
Correct/improve dragbox docs
Add ol.style.Icon#getImageSize
Add write support to KML format
Add export button to kml example
Add an exampleNS.strToBase64 function

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Base64_encoding_and_decoding
Use exampleNS.strToBase64 in kml example
Minor change to the example externs file
Create valid KML documents

Thanks @bartvde.
Hit detection for features drawn at pre/postcompose
Clone skippedFeatureUids_
Use ol.xml.setAttributeNS for xmlns attributes
Fix nodes order in Placemark and IconStyle
Defer selection/deselection
Finish the replay group after dispatching the compose event
Flush the vector context after replaying the batch
Do not "export" ol.render.Event#replayGroup
Use string values for ol.source.State enum

Many user-facing enums are string values and we document use of the string values rather than more confusing enum reference or the numeric values.
Merge pull request #2247 from pagameba/source-state

Use string values for ol.source.State enum