Adds a wrt-init kind of on the model of git init for starting a stub
directory with wrt.json, archives/, publish/, and templates/.

Also starts to tweak POD a bit.

This is based on a recommendation from CPANTS:

https://cpants.cpanauthors.org/release/BRENNEN/App-WRT-v4.0.1

> Add a 'repository' resource to the META.yml via 'meta_add' accessor
> (for Module::Build) or META_ADD parameter (for ExtUtils::MakeMaker).

I went and read:

https://pause.perl.org/pause/authenquery?ACTION=pause_namingmodules

Realized I should probably not name this something with an inscrutable
top-level namespace.  WRT is still inscrutable, I guess, but at least
it's now under App.

- Renames all modules, fixes tests (such as they are)
- Zaps old t/validate/ stuff

This hadn't been in use for a while anyhow.

- create an index.html with new entries
- create an /all/index.html with a list of all entries
- create a /feed containing an atom feed of the most recent month
- a paragraph on requirements in the installation section
- copyright date through 2017

I never did get around to writing one of these.  At this point in history,
I guess I don't regret the omission.

This will probably eventually bite me, since it could overlap with other
entry display logic, but it doesn't seem to break anything at the moment.

This is a fairly p1k3-specific thing.

- adds include_process() in WRT::Markup
- moves eval_perl() into WRT::Markup.  The way object instances are
  composed (and instance methods called) here still feels pretty janky,
  and this does nothing to help the situation.
- changes all existing $root_dir instances to $entry_dir; adds a $root_dir
  which represents the root of the archive (top-level folder containing
  the wrt.json file)

I'd be worried about the $root_dir change if I thought this module had a
single other user in the wild, but I strongly doubt that it does.  If I
am wrong and you are that user, I apologize sincerely in advance.

The include feature still has fairly unsettled semantics, but it gets the
whole thing much closer to a usable site generator.

These used to live in bpb-kit; moving them in here since they're specific
to the wrt format.

Now uses:

  wrt display
  wrt render-all
  wrt fcgi

Rename to wrt

It's shorter and the letters are all right there on the keyboard.