Use epsilon value to compare duplicate polyline positions.
Add tests.
Update CHANGES.md.
Adjust epsilon value when comparing polyline vertices forduplicates.
Add relative tolerance tests to Math and Cartesian*.
Use relative tolerance test to remove duplicate positions from polylines.
Update PolylineGeometry and PolylinePipeline tests.
Add tests for equalsEpsilonRelative functions of Math and Cartesian*.
Updates from review.
Merge remote-tracking branch 'origin/master' into polylineGaps
Update CHANGES.md
Merge branch 'master' into polylineGaps

Conflicts:
	CHANGES.md
Merge branch 'master' into polylineGaps

Conflicts:
	CHANGES.md
Changes based on offline discussion with @shunter.
Fix tests.
Improve font rendering and outlines

To remove jaggedness of outlines, we now set context.lineJoin to `round`.
After doing this, I realized that lots of letters where still being cut
off on both sides.  It turns out the bounding width of the letter that
we compute is actually wider than the browser computed width.  Using our
own values prevented the cutoff.

I still want to test this more with a variety of fonts and settings to
make sure it's good, any help in that area is appreciated.

I used thie jsFiddle to compare our per-letter rendering to typical "whole"
word rendering in browsers: http://jsfiddle.net/AbdiasSoftware/48m4B/2/
We should match the bad kerning and all.

Fonts also look better at smaller resolutions now, so I removed the label
hack I had in simple.czml.

Fixes #1141
Improved extruded polygon performance and slightly improve combining geometries. Also reduce memory allocations.
More extruded polygon optimizations.
Don't double request font outline width.

This was previously a hack to try and make fonts looks better in Cesium.
Minor cleanup.