fixed error with missing quotes on array index name
added a check to ensure $maps[$dest]['unicode'] exists before we test to see if it's an array
error checking added in build scripts
included missing php tags
updated optimize to use pngout (pngout-static is no more)
updated build_image to default to vertical sprite mode (better size/compression, over 100k reduction in sprite file size)
updated build_image to support --grid & -g for users that wish to stick to the grid layout
updated css to use new vertical sprite
emoji.png has been optimized via pngout