[pytest-dev] preparing a breaking internal change - splitting Session into the node and the plugin

[RonnyPfannschmidt]

Hi everyone,

since a while now the fact that session is both a Node and a plugin has
created some interesting issues

(like the compatproperties that cant warn correct due to pluggy and
fixture scanning)

i'd like to elevate those issues by slitting the plugin part and the
session part into different classes.

while affecting other users should be next to impossible, its still a
breaking change.

as such i believe it should be prepared in turn with a major pytest
release thats also removing more badness/slack

(this also creates some unique issue, since the very structure i want to
break appart preventssane deprecation warnings for some parts)


i#d like to get some opinions on what others think of this


-- Ronny