v4.2.3

Fixes

• Handle images whose URLs don’t end in a file extension that allows us to identify the image’s MIME media type. In these cases, use the generic image MIME type (e.g. in inline data: URLs when the --inline flag is used) and the .image file extension (e.g. when bundling external resources for EPUBs). Support for these may vary with the browser / EPUB reader. (#174)