Unused variable `py-python-major-version' removed
Unused stubs python2-mode, python3-mode, jython-mode removed

Related variable `py-exec-string-command' removed
Unused `py--shell-complete-intern' removed
Unused `py-comint--complete' removed
Some more shell tests
Signal error if `make-comint' fails
`py-shell' - setup `with-current-buffer'

make sure settings get the right buffer

`python-shell-completion-setup-code' renamed `py-shell-completion-setup-code'
`py-complete--base', delay introduced

seems needed at windows

`py-shell-name', `py-python-command' defaults normalized