start work on #44 - get pixel
use v8 array as return type for getPixel
validate getPixel arguments. return a color object
add tests for getPixel
add getPixel docs to the readme
Merge branch 'feature/decree-color-type' into feature/get-pixel
Merge branch 'feature/decree-custom-types' into feature/get-pixel

Conflicts:
	lib/Image.js
fix previous merge

'getPixel' was accidentally removed
Merge branch 'feature/get-pixel' into feature/set-pixel

Conflicts:
	lib/ImagePrototypeInit.js
remove 'setPixel' from random batch test generator

...as it may sometimes fail due to our of bounds coordinates when image
is randomly resized (for example).