www/pelican: Prefix according to Python conventions

[koobs]

Summary

Proposed commit log:

www/pelican: Prefix according to Python conventions

- Rename (move) according to Python package naming conventions [1]
- Switch temporarily to GITHUB for source files until missing content
  files for the test suite is merged/fixed [2]
- Add python (virtual category) to CATEGORIES
- Add LICENSE_FILE
- Add OPTIONS for Markdown and Syntax Highlighting, they are OPTION'al 
  features
- Add MARKDOWN and SYNTAX to OPTIONS_DEFAULT (for package convenience).
- Use OPTIONS helpers for TESTS option.
- Refactor TEST_DEPENDS so it only declares tests_require, moving the   
  RUN_DEPENDS assignment to TESTS_BUILD_DEPENDS.
- Rename TEST option to TESTS to match other Python ports, and tweak 
  description to canonicalize
- Deprecate OPTIONSFILE override (no longer necessary)
- Canonicalize regression-test target, so it gets the setuptools wrapped
  setup.py arguments for proper 'test' command support.
- Re-order makefile sections (DEPENDS|USES|OPTIONS)
  
While here:

- Add MOVED entry
- Update www/Makefile

[1] https://wiki.freebsd.org/Python/PortsPolicy
[2] https://github.com/getpelican/pelican/pull/1793

Approved by: maintainer
DiffRev: DXXX

Test Plan

portlint: looks fine.
porttest: OK (poudriere)
unittest: Ran 170 tests in 6.668s - FAILED (errors=3, skipped=18)

test_basic_generation_works ... ERROR
test_custom_generation_works ... ERROR
test_custom_locale_generation_works ... ERROR

[koobs]

Merge head (r394416, update to 3.6.3)

[jlaffaye]

I thought the py prefix is required for python package, not for executable written in python.

I'd prefer the SYNTAX option to be on by default for the package.

[koobs]

In D3328#71642, @jlaffaye wrote:

I thought the py prefix is required for python package, not for executable written in python.

That's been the case in the past, but there have been and will continue to be naming conflicts unless all python ports (particularly those listed in PyPI/CHEESESHOP) are py- prefixed, see:

https://wiki.freebsd.org/Python/PortsPolicy#Naming

I'd prefer the SYNTAX option to be on by default for the package.

Done, I'll update the diff shortly

[koobs]

Mark the SYNTAX option as a default option

[jlaffaye]

Please commit :)