Make sure updateol works multiple times
Update ol3 vector-api to https://github.com/openlayers/ol3/commit/057cda42be7f6b27dcb9106dd00870570bcef139
Using clear to remove all features from a vector layers/source. Thanks Tom!
Merge pull request #852 from geoadmin/dev_styles_clear

Update ol3 vector-api, using new functionality