Invisible part setting field.
L18n compliance for pressbooks-book cover page, other l18n fixes.
Colon after copyright in webbook footer.
Initial implementation of invisible parts.
Merge branch 'invisible' into dev
Prince styles for invisible parts.
Part that have content are new linked in TOC on webbooks.
Added 5" x 8" page size for PDFs.
SVG files are now enabled.
Parts with content are now included in back/forward navigation in webbooks.
Don't show invisible parts in back/forward navigation in webbooks.
Extraneous parenthesis.
Merge branch 'dev' into epub3
NCX generation now supports invisible parts.
Maybe fix EPUB NCX validation error?
Revert "SVG files are now enabled."

This reverts commit 213c8a269db0a3c566baed35772813945ca53cf3.
replacing deprecated wp calls
Merge branch 'dev' of https://github.com/pressbooks/pressbooks into dev
Merge pull request #49 from bdolor/dev

replacing deprecated wp calls
Merge branch 'dev' of https://github.com/pressbooks/pressbooks into dev