Improved EPUB Font Handling: Generation of CSS @font-face Rules

This release adds additional functionality to the EPUB transformation type's support for embedded fonts. It is now possible to automatically generate a CSS file that contains @font-face rules for each font specified in the font manifest specified at run time.

Also fixed an issue with the specification of user CSS files at runtime. The EPUB transform now correctly uses the normal arg.csspath parameter to specify the location within the generated EPUB for the user-specified CSS. Also added a new parameter, epub.copy.system.css, to enable not including the OT-provided CSS files in the EPUB.

No other changes to the other transforms. Updating the release packages for convenience.

NOTE: This version works, or at least doesn't fail, with OT 2.1.1 but may or may not work with later 2.x versions. General support for 2.x is still an open action item.