Added support for rendering enumerations in ordered lists and for list-style

[matthias-christen]

Summary

This PR adds support for rendering the enumerations (bullets, numbers, etc.) in ordered and unordered lists and for list style images.
For the actual formatting, an external package is used (https://www.npmjs.com/package/liststyletype-formatter), I hope that's OK.

This PR fixes/implements the following bugs/features

• Feature: support for rendering enumerations in (un)ordered lists (list-style-type, list-style-position, list-style-image)

Explain the motivation for making this change. What existing problem does the pull request solve?

More accurate rendering of (un)ordered lists.

Test plan (required)

Added tests/reftests/list/liststyle.html, which tests some more list styles in addition to the already existing tests, in the tests/reftests/list folder.

Closing issues

Fixes #177
Fixes #308

[niklasvh]

Thanks for the PR! I started looking through this over the weekend.

Few things that need to be resolved (which I started fixing already):

• The list style should not be tied to LI tagName but instead display: list-item as a div or any other element can have a list item just as long as its display is list-item same way a LI won't have a list item if you change it's display.
• Supporting all the different variants of list styles without any build time options to selectively choose which ones/languages to support might increase the package size excessively without much gain. Same applies with changes to word-break etc support for different languages where I was planning on tackling that issue. Ancient versions of html2canvas had list style support, with a few of the variants supported: https://github.com/niklasvh/html2canvas/blob/0.4.1/src/Generate.js#L391
• Move the list style parsing out of ListItem and into parsing/listStyle

As said I am working on fixing those issues already so no need to change the PR.

[andersborgabiro]

At least I'd be happy to be able to apply at least unordered bullets at all, without too much "magic", as in my case a user edits content via TinyMCE. It's possible to apply custom styles to tags, as long as "li" is used (as that's what a user chooses in the toolbar) rather than something else completely.

[niklasvh]

All types of list-style are supported for now, smaller subsets with specific languages will be worked with the word breaking and other language dependent features.

[andersborgabiro]

Great! Something fun to evaluate during the holidays :).

[tininess]

All types of list-style are supported for now, smaller subsets with specific languages will be worked with the word breaking and other language dependent features.

I using the newest pre-release but not work :( https://jsfiddle.net/boLxkgj8/265/

[RUSSCITY]

All types of list-style are supported for now, smaller subsets with specific languages will be worked with the word breaking and other language dependent features.

I using the newest pre-release but not work :( https://jsfiddle.net/boLxkgj8/265/

ok, you was not using the latest version, now it looks like it works:
https://jsfiddle.net/jeavhg05/4/