Plugin Meta stuff

[ghost]

taken over from #516

sadly I screwed up the branch naming but as there is no longer a "master" branch here, I've decided to ignore it and just delete the branch afterwards.

I have tried to adress the concerns voiced in the original PR in order to not let the contributions of @20zinnm go stale.

[Spongy]

A preview for this pull request is available at https://cdn.rawgit.com/Spongy/SpongeDocs-PRs/1042636/.

Here are some links to the pages that were modified:

• modified: https://cdn.rawgit.com/Spongy/SpongeDocs-PRs/1042636/plugin/plugin-class.html
• modified: https://cdn.rawgit.com/Spongy/SpongeDocs-PRs/1042636/plugin/plugin-meta.html

Since the preview frequently changes, please link to this comment, not to the direct url to the preview.

[stephan-gh]

It might make more sense to link to the Javadocs of Dependency.version here https://jd.spongepowered.org/5.0.0/org/spongepowered/api/plugin/Dependency.html#version--

[Inscrutable]

A rolling PR gathers no FLARD. What's the status of this at present?

[Inscrutable]

Oh dear. Where is our esteemed @Saladoc and what will become of this PR?
Is this complete enough to merge, or are there any spare brains in the gallery that could pick up the pieces here (again) and try to get this stuff finished?

[dualspiral]

From my point of view (feel free to ignore), I don't think the Code Modularisation page is complete enough to merge, certainly, and isn't really anything to do with modularisation in itself, though the document there can be of use if you do modularise in a certain way. Modularisation of code can take many many forms, one of which is splitting up into multiple plugins. I feel like the current Code Modularisation page would be better being part of an "Interacting with Other Plugins/Plugin Interop" page (#228), because that's all you've got there so far.

As for the plugin meta page, I think the changes there are reasonable.