Introduce new user custom variable `ein:on-kernel-connect-functions' which is an
abnormal hook called after a kernel connection is made. All functions in the
hook are called with the connected kernel as an argument.
This replaces the old, unused `ein:kernel-run-after-start-hook' function.
Some caveats: completion and tooltips using the kernel are no longer available
as ein-pytools has been mostly neuterd. Cell autoexecution also been removed.
`company-backends' is special-variable-p so I don't believe it can be
buffer-local.
avoid eager loading of ess or julia.
if one changes the minimal tested version of emacs, one should `make
README` to reflect. Also, reverted back to 25.1 because #509.
no need for evm under osx (purcell).
restore a completion test (after disabling company-frontends).
Hard to reproduce exactly what is happening, but try to work around the
possibility of a company completion popup appearing in the buffer or minibuffer.
Unfortunately, no good way to test font-lock as font-lock-mode won't
activate under noninteractive ecukes (can try --no-win or --win, but
won't fly under travis)
In practice, polymode font-lock bugs often manifest themselves much as
issue #456 did. The rear-nonsticky property on the input prompt gets
washed away by font-lock and brokenness ensues.
Some users run jupyter via `jupyter-notebook` instead of `jupyter`,
and break because we unilaterally impose the "notebook" subcommand.
Those users can now:
```
M-x customize-group ein
Jupyter Server Use Subcommand: Omit
```