devel/py-python-dateutil: Move devel/py-dateutil to devel/py-python-dateutil

- Convert to USE_PYTHON=pep517
- Bump PORTREVISION of dependent ports for dependency change
- While I'm here, update audio/py-pyradio to use PYTHON_PKGNAMEPREFIX instead of
PKGNAMEPREFIX for *_DEPENDS

all: remove explicit versions in USES=python for "3.x+"

The logic in USES=python will automatically convert this to 3.8+ by
itself.

Adjust two ports that only had Python 3.7 mentioned but build fine
on Python 3.8 too.

finance/quickfix: mark BROKEN with PYTHON

libtool: compile:  c++ -DHAVE_CONFIG_H -I. -I../.. -I -I. -I.. -I../.. -I../C++
-DLIBICONV_PLUG -DPYTHON_MAJOR_VERSION=3 -Wno-unused-variable
-Wno-maybe-uninitialized -O2 -pipe -DLIBICONV_PLUG -fstack-protector-strong
-fno-strict-aliasing -DLIBICONV_PLUG -Wall -ansi
-Wno-unused-command-line-argument -Wpointer-arith -Wwrite-strings
-Wno-overloaded-virtual -Wno-deprecated-declarations -Wno-deprecated -std=c++0x
-MT _quickfix_la-QuickfixPython.lo -MD -MP -MF
.deps/_quickfix_la-QuickfixPython.Tpo -c QuickfixPython.cpp  -fPIC -DPIC -o
.libs/_quickfix_la-QuickfixPython.o
warning: unknown warning option '-Wno-maybe-uninitialized'; did you mean
'-Wno-uninitialized'? [-Wunknown-warning-option]
QuickfixPython.cpp:175:11: fatal error: 'Python.h' file not found
          ^~~~~~~~~~
1 warning and 1 error generated.

Reviewed by:	portmgr, vishwin, yuri
Differential Revision:	<https://reviews.freebsd.org/D40568>

Remove WWW entries moved into port Makefiles

Commit b7f05445c00f has added WWW entries to port Makefiles based on
WWW: lines in pkg-descr files.

This commit removes the WWW: lines of moved-over URLs from these
pkg-descr files.

Approved by:		portmgr (tcberner)

Add WWW entries to port Makefiles

It has been common practice to have one or more URLs at the end of the
ports' pkg-descr files, one per line and prefixed with "WWW:". These
URLs should point at a project website or other relevant resources.

Access to these URLs required processing of the pkg-descr files, and
they have often become stale over time. If more than one such URL was
present in a pkg-descr file, only the first one was tarnsfered into
the port INDEX, but for many ports only the last line did contain the
port specific URL to further information.

There have been several proposals to make a project URL available as
a macro in the ports' Makefiles, over time.

sysutils: remove 'Created by' lines

A big Thank You to the original contributors of these ports:

  *  <jsmith@resonatingmedia.com>
  *  Aaron Dalton <aaron@FreeBSD.org>
  *  Aaron Landwehr <aaron@snaphat.com>
  *  Adam Weinberger <adamw@FreeBSD.org>
  *  Adrian Chadd
  *  Adrian Chadd <adrian@FreeBSD.org>
  *  Akinori MUSHA aka knu <knu@idaemons.org>
  *  Alan Eldridge <alane@FreeBSD.org>
  *  Alan Eldridge <alane@geeksrus.net>
  *  Aldis Berjoza <aldis@bsdroot.lv>
  *  Alex Deiter <alex.deiter@gmail.com>

Cleanup: for ports under s* categories, drop redundant GH_* knobs.

Remove # $FreeBSD$ from Makefiles.

Drop python 2.7 support from a few ports

With hat:	portmgr

Add sysutils/py-tarsnapper 0.4

A wrapper around tarsnap which does two things:

* Lets you define "backup jobs" (tarsnap invocations) in a
  config file, though on its own this has little advantage over just
  using a a shell script.
* The ability to expire old backups using a Grandfather-father-son
  backup scheme.  This feature can be used in conjunction with
  tarsnapper backup jobs, or standalone, to be applied to any existing
  set of tarsnap backup archives, regardless of how they have been
  created.

WWW: https://github.com/miracle2k/tarsnapper