v4.2.0 of cached_network_image_ce

Community Edition Flutter library to load and cache network images. Can also be used with placeholder and error widgets. Changelog excerpt: - **Feature:**Added SVG support via new unsupportedImageBuildercallback - New UnsupportedImageFormatExceptionthrown when image format is not supported by Flutter's standard codec - New ImageFormatDetectorutility with content sniffing for SVG detection - Images are still cached normally; only rendering path differs - Example app updated with SVG demo using flutter_svg - 24 new tests added (18 format detection + 6 widget integration) - See README for usage example