VisualEditor is usually not enabled in talk namespaces... but
sometimes it is. And when users see the button to edit with VE,
they're going to click it and expect to be able to sign their posts.
This tool is only loaded on talk pages and pages in additional
namespaces defined in $wgExtraSignatureNamespaces.
Code adapted with small tweaks from my own gadget
<https://meta.wikimedia.org/wiki/User:Matma_Rex/visualeditor-signature.js?oldid=13461327>,
which is already available under the MIT license.
Changes include:
* The tool is now always visible if the wiki allows signatures in any
VE namespaces, but disabled when not allowed in the current namespace.
* Register '~~~~' sequence to insert the signature.
* Code style tweaks for stricter lint checks in this repository.
* Documentation corrections.
Swedish translation provided by André Costa (already credited
as a translator as Lokal_Profil).
Depends on changes in VisualEditor core:
* I89fe53890ab59d12260ea6b41de802c38c24e8b9
* I14cd7efac521687ea38580341ae08ddc522edeeb
Bug: T53154
Change-Id: I6be5fb2118cf3eef5098d4c5320228aa81411ccb
