[Enhancement] writer: Footnote / Endnote Styles according to standards

It would be helpful to have preconfigured Footenote/Endnote styles, as part
of the styles options.

Within the *Styles* menu we could have a new submenu titled
*Footnote/Endnote*.

The basic idea is to have inside this submenu preconfigured footnote/endnote
styles according to the styles most used in professional, academic,
scientific, technical or artistic reports, among them:

*APA
CHICAGO
MLA
Turabian
ISO 690
IEEE
Harvard-Anglian
GOST*

Ramon, *

Using the existing Bibliography sample data base provides considerable
function already, based on Harvard style as I understand.

https://wiki.documentfoundation.org/images/2/23/WG4212-TOCsIndexesBiblios.pdf
https://wiki.documentfoundation.org/Referencing_Systems_in_LibreOffice

And frankly this is already well handled by 3rd Party extension--I'm a fan
of Zotero standalone (Windows) and cross-platform (via Firefox) . The
LibreOffice plugin(s) allows application of any .CSL and effective styling
of the parenthtical, footnote, endnote and bibliography. And have not used
it recently but the Mendely project is equally functional.

But always room to improve: have open BZ enhancment for this in tdf#94418
<https://bugs.documentfoundation.org/show_bug.cgi?id=94418> and duplicate
tdf#95315 <https://bugs.documentfoundation.org/show_bug.cgi?id=95315> .

Preliminary UX/Design team discussion ~Sep 2015 in
https://docs.google.com/document/d/1IQ2_dFlWodb3NI9VFy1l4_ZmKpJgoyATYvOmB-0yUcY/edit

As to doing it fully ourselves (and maintaining it), IMHO we should
concentrate on providing the style framework for those 3rd party projects
implementing the full set of .CSL--e.g. Zotero or Mendely rather than
struggle to provide just the few major styles.

http://citationstyles.org/
https://www.zotero.org/styles

Stuart