Make 3.0.0 release

[kghbln]

• [x] Update ".travis.yml"
• [x] Update "RELEASE NOTES" (rem: https://github.com/SemanticMediaWiki/Mermaid/pull/55#discussion_r466971315)
• [x] Update "README"
• [x] Update "extension.json"
• [x] Create tag
• [x] Update "extension.json" to start development of new version

[kghbln]

As a result of #47 once completed.

[akuckartz]

As a result of #47 once completed.

It seems to be completed ;-)

[kghbln]

Latest master available on sandbox for testing and extending by additional examples.

The only irritating thing I realize now it the overflow bars which we are unconditionally getting. I believe this needs to be tweaked. @cicalese I think this enhancement was originally created by you and it worked in previous releases, i.e. we got the bars only for oversized charts etc. Perhaps you have an idea as to why this is now shown unconditionally.

[cicalese]

@kghbln I did not see the scrollbars in the examples, but they are probably due to

/** Mermaid
 * Add scrollbars to wide graphs
 */
.ext-mermaid > div {
    overflow: scroll;
}

which as introduced into MediaWiki:Common.css in https://sandbox.semantic-mediawiki.org/w/index.php?title=MediaWiki:Common.css&diff=prev&oldid=47241 due to #41. If you don't want to add that unconditionally, maybe you could use TemplateStyles to add it only to pages that need it?

[kghbln]

@cicalese

I did not see the scrollbars in the examples

Hmm, probably a browser related issue. This is what Fx shows:

but they are probably due to ... which as introduced into MediaWiki:Common.css in https://sandbox.semantic-mediawiki.org/w/index.php?title=MediaWiki:Common.css&diff=prev&oldid=47241 due to #41

Ah, I figured this was part of the CSS shipped with the extension. That explains it. Thanks a lot for the pointer.

If you don't want to add that unconditionally, maybe you could use TemplateStyles to add it only to pages that need it?

No, since the latest release it really looks ugly, so an alternative solution probably involving a template using TemplateStyles is the best option here. Thanks again for the suggestion!