Add support to EPUB 3 series and series number

[mddanish00]

Adding support to EPUB 3 series and series number when Create EPUB 3 is selected. Both calibre:series and calibre:series_index still retained in EPUB 3 version for compatibility reason.

The result of new additions for EPUB 3 content.opf:

<meta name="calibre:series" content="Whatever It Is" />
<meta name="calibre:series_index" content="4" />
<meta property="belongs-to-collection" id="series">Whatever It Is</meta>
<meta refines="#series" property="collection-type">series</meta>
<meta refines="#series" property="group-position">4</meta>

Tested by packing EPUB with Create EPUB 3 is selected and Series and Volume filled out to make sure.

References

• https://www.w3.org/TR/epub-33/#sec-belongs-to-collection
• https://www.w3.org/TR/epub-33/#sec-collection-type
• https://www.w3.org/TR/epub-33/#sec-group-position

[gamebeaker]

I closed and reopened the PR to re trigger the github actions check.

[gamebeaker]

@mddanish00 i don't really understand the reason for "collection-type" to exist. But as it is in the spec lgtm.