`py--fill-docstring-base' again

py--send-receive-delay renamed `py-python-send-delay'

New customizable `py-ipython-send-delay'

Execution through IPython needs extended delay

Unused `py-completion-delay', `py-ac-length-min' removed

`py--delay-process-dependent' new internal function
Call a `py-ipython-send-delay' or `py-python-send-delay' according to
process
`py-indent-or-complete' fixed

Completion from inside a shell

py-ert-imports-in-interactive-shell-lp-1290709 failed
`py-send-string' use `process-send-string', not `comint-send-string'
`py--execute-file-base' use `process-send-string', not `comint-send-string'
`py--fetch-comint-result', `py--postprocess-comint' rewritten

`py--shell-manage-windows', `py--send-to-fast-process', `py--filter-result'

Partially revert previous commit

Use `comint-send-string' - keep previous prompts in buffer fontified
`py-send-string' make sure ends at point-max, bug?

`py-send-string', `py--postprocess-comint' delays, minor changes
`python-extended-executes-test'.el

py-execute-def--- forms fixed

Some tests like `py-execute-buffer-ipython-switch-test' fail in
batch-mode but succeeds interactively:
moved into python-mode-test.el,
command `py-run-interactive-tests'
`python-extended-executes-test'.el

py-execute-def--- forms fixed

Some tests like `py-execute-buffer-ipython-switch-test' fail in
batch-mode but succeeds interactively:
moved into python-mode-test.el,
command `py-run-interactive-tests'