Introduce new resize option - preserve_headers, a way to strip off meta headers completely in order to reduce the final size even more. Add some code to aid garbage collection.
Take into account Orientation tag, when resizing JPEGs and not preserving meta headers. Address #640, #572, #540. Update moxiecode/moxie@607acd9afab20022dfce8f23236c14e2d0f19d01.