Don't attempt to fit views to empty extents
Merge pull request #1426 from twpayne/view2d-fit-empty-extent

[master] Don't attempt to fit views to empty extents
Export ol.proj.Projection#getUnits

Fixes #1365
Merge pull request #1438 from fredj/proj-export-getUits

Export ol.proj.Projection#getUnits
Make build.py compatible with Python 2.6
Merge pull request #1447 from probins/build

Make build.py compatible with Python 2.6
Merge remote-tracking branch 'openlayers/master' into vector-api