improve namespace support

[MrTango]

make sure that we can create packages in different formats:

• collective.mypackage
• collective.plone.myaddon
• mypackage
• my-package
• collective.my-package

[mamico]

Manually tested with

% plonecli -V
        plonecli : 2.4
        bobtemplates.plone: 6.0b16.dev0
 % plonecli create addon NAME
 % cd NAME
 % plonecli build test

• collective.mypackage - works

• collective.plone.myaddon - works

• mypackage and my-package fail during plonecli create

% plonecli create addon mypackage
...
Error: 'mypackage' is not a valid packagename.
Please use a valid name (like collective.myaddon or plone.app.myaddon)

• collective.my-package fails during plonecli build

error in collective.my-package setup command: 'NoneType' object has no attribute 'group'
While:
  Installing.
  Processing develop directory '.../collective.my-package/.'.

An internal error occurred due to a bug in either zc.buildout or in a
recipe being used:
Traceback (most recent call last):
  File ".../collective.my-package/venv/lib/python3.8/site-packages/zc/buildout/buildout.py", line 2250, in main
    getattr(buildout, command)(args)
  File ".../collective.my-package/venv/lib/python3.8/site-packages/zc/buildout/buildout.py", line 717, in install
    installed_develop_eggs = self._develop()
  File ".../collective.my-package/venv/lib/python3.8/site-packages/zc/buildout/buildout.py", line 960, in _develop
    zc.buildout.easy_install.develop(setup, dest)
  File ".../temp/collective.my-package/venv/lib/python3.8/site-packages/zc/buildout/easy_install.py", line 1120, in develop
    call_subprocess(args)
  File ".../collective.my-package/venv/lib/python3.8/site-packages/zc/buildout/easy_install.py", line 172, in call_subprocess
    raise Exception(
Exception: Failed to run command:
'.../collective.my-package/venv/bin/python3', '/tmp/tmp73x59m63', '-q', 'develop', '-mN', '-d', '.../collective.my-package/develop-eggs/tmpgn8z91m3build'

[mamico]

closed by #522