Add manifest.json for PWA functionality

[albacoretuna]

On phones that support progressive web apps, adding dokuwiki to
home screen will make it open in full screen which is nicer.

fixes #2156

[phy25]

Just dropping my two cents here, is it necessary to add a new lib/manifest folder? In the long term only one single manifest file is required. Maybe you can merge it into lib/styles folder.

[splitbrain]

What is the php file for when all you do is deliver a static manifest file? This could be easily done by the web server.

It would make sense to dynamically create the manifest though when using the wiki's title instead of a hard-coded "DokuWiki".

[albacoretuna]

@phy25 thanks for your review. I just thought because it's not a stylesheet it will be confusing to put it in lib/styles

@splitbrain you're right, I just assumed I should exactly follow how jquery is included.

How does it look now?

By the way thanks for acting nicely on my first PR, it was a quick review :)

[micgro42]

I like this a lot! I think starting with a static JSON file is a good idea for now. 🙂

I see many possible extensions for future pull requests:

• Using DokuWiki's title and tagline, (as suggested by splitbrain)
• using a placeholder from the style.ini as background color
• Providing user-defined icons
• adding a config option to modify the manifest's display key
• etc.

But again, these are things for the future. Or maybe a plugin that utilizes a metaheader event?

[michitux]

As it is now, every DokuWiki instance will appear the same unless the admin of that wiki customized that file (which will be reverted on every upgrade). I don't think having this by default with no way to easily disable it (that persists across upgrades) is desirable for any wiki but dokuwiki.org.

I think the feature in general is nice, but I would at least suggest the following features:

• Use the title and tagline of the wiki so the default is okay for most wikis
• Use a configuration cascade for finding the JSON file and allow overriding it with a file in the configuration directory (similar to user styles).
• It would be nice to re-use the existing icon customization options. I think the "apple-touch-icon" should already be the right type/size of icon.

[albacoretuna]

I'll close this in favor of #2241