Allow specific files and multiple inputs for picture testing tools.

Changed the render_pictures, bench_pictures and test_pictures.py so that multiple inputs can be given. Furthermore, specific files can also be specified.

Unit tests have also been added for picture_utils.cpp.

Review URL: https://codereview.appspot.com/6345054

git-svn-id: http://skia.googlecode.com/svn/trunk@4486 2bbb7eff-a529-9590-31e7-b0007b416f81
6 files changed