remove Python2 hybridation code

[a-detiste]

print() is available since Python 2.6

https://wiki.debian.org/Python3-six-removal

[swt2c]

Probably don't need this...we can drop support for Python 2.

[a-detiste]

so let's remove all sixusage ?

[a-detiste]

... and the vendored copy living as wx/lib/pubsub/py2and3.py

[bewczardski]

This is changing the value from a list to a scalar value which is now causing crashes later on in the source. I converted all in INTEGER_TYPES to == INTEGER_TYPES and it fixed it. Should probably update the name to reflect the change as well.

if type(itemOrId) in INTEGER_TYPES: < line 598

Another example:

    """
    A list event holds information about events associated with :class:`UltimateListCtrl`
    objects.
    """

    def __init__(self, commandTypeOrEvent=None, winid=0):
        """
        Default class constructor.
        For internal use: do not call it in your code!

        :param `commandTypeOrEvent`: the event type or another instance of
         :class:`PyCommandEvent`;
        :param `winid`: the event identifier.
        """

        if type(commandTypeOrEvent) in INTEGER_TYPES:

[a-detiste]

Thanks for the review The right thing to do is to get rid of INTEGER_TYPES altogether: ``` -if type(commandTypeOrEvent) in INTEGER_TYPES: +if isintance(commandTypeOrEvent, int): ```

[jmoraleda]

I agree with this PR. I also agree with removing all six usage.

[komoto48g]

I agree with dropping support for Python 2.
IMHO, this PR is too aggressive and the first commit (removing print_) would be more acceptable if it was a separate PR.

From "https://wxpython.org/pages/contributor-guide/",
5. Do not put more than one fix/feature in the same branch or PR. Make a new distinct branch and PR for each of them.

[a-detiste]

I m on Holliday. Anyone can cherrypick the first commit that removes py2.6< compatibility if it tastes them,
I ll redo this work in smaller pieces when I get back.

[a-detiste]

At first there was only this one first commit untill I got asked to proceed further