feat: add Masterlingo visible-nodes-update event to paginator

Support annotation and tts on PDFs

Fix documents without lang attribute or XHTML namespace for TTS

Fix TOC grouping

Properly constrain the max width and height of images

Support duokan-page-fullscreen in spine to display cover image in fullscreen

Support loading system custom fonts

Fixed exception on closing popup footnote

Allow overriding the padding of the root html

Add content field in OPDS feed

Fix incorrect grouping of some subchapters (#7)

Add getCFIProgress to get page number for given CFI

Fix phantom subchapter entry when fragment-only children share a file (#6)

TTS: improve abbreviations processing (#4)

Add atStart and atEnd for fixed layout renderer