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
Export ol.Observable

This is so on, un and friends appear in the api docs.
Use goog.style.getContentBoxSize to calculate map size

This takes into account any border.
Merge pull request #1450 from elemoine/observable

Export ol.Observable
Merge pull request #1451 from twpayne/get-content-box-size

Use goog.style.getContentBoxSize to calculate map size