port select and python ...

[petr]

Hi all,

I realise that there quite some inconsistency in the naming of select port naming, select groups and targets names when port select is used with python. 

* Some python related select ports use a `py-` prefix, most do not ….

py-cairosvg_select              
py-cssselect                    
py-html2text_select             
py-pss_select                   
py-sympy_select

* Same for the name of the group

* For the version target names patterns:

${real_name}{python.version}
${real_name}-{python.version}
py{python.version}-${real_name}

Is there a recommend way to name all these? Or are we free to pick anything we like? 
Should there be some recommendation?

Thanks!
~petr