Merge pull request #1507 from mpickering/master

Images are now relative to manifest file.
Merge pull request #1508 from mpickering/master

EPUB: Fixed another mediabag related regression..
Docx Reader: Added recognition of sym element in paragraphs
lib: Added symbol.txt and file to generate codepoint to unicode mapping
Added Text.Pandoc.Readers.Docx.Fonts
Added test for sym element
Docx Parse: Recognises code points in sym elements which are in the private range
Docx Tests: Updated for reading sym element
Merge pull request #1509 from jkr/symbol

Parse "w:sym"
Improved EPUB Tests

Rewrote features test to remove all unimplemented features.

There are now all three examples of where an image can be included in
the test.
  1. Cover image
  2. As a spine elemnt
  3. In the document

Tests have also been added to make sure that the mediabag contains all
these images after processing.