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Increased accuracy of anti-aliased pixels comparison.

Adds Node 0.10 support for command line and tests.

• Much more accurate anti-aliased pixels detection algorithm #2
• Display transparent pixels as white rather than gray in diff

Note a breaking API change: antialiasing argument (number, 1 by default) is replaced with includeAA (boolean, false by default). Anti-aliasing detection is still enabled by default but always happens with 1 pixel radius.

Fixed minor bug in color difference calculation.

Use premultiplied Y'UV colorspace for color comparison, making it more in line with human perception of color.

First release.