`py-fast-process' doesn't need temporary buffer/file

Tests improved
`py--execute-base' refactored

New function `py--execute-base-intern'
If a shell is called from a program, banner needs some delay

Make `py-shell' distinguish interactive calls
`py--execute-base-intern' refactored

New function `py--send-to-fast-process'
UnicodeEncodeError-lp:550661 test fixed
custom-add-option python-mode-hook removed
execute-buffer, lp:1338134

fixed

New internal function `py--store-result-maybe'