better printing of In/Out prompts
rudimentary history support (current session only)
some more todo items
Ctrl-W word splitting on ., (, and =
delete word when it ends with word separators: .,(
use Escape to clear docstrings

it takes a while to kick in (half a second?), but better than nothing.
This will be particularly useful for when the tooltip is above the input
line and is blocking the last set of outputs
updated TODO
potentially expensive but working history browsing

this fetches the current history's entire session on every execution.

It would be fairly easy to make this happen *only* after an initial
'cursor up' motion, and also chunk it to not grab the full thing.
less greedy history fetching.

set dirty bit on execute, and refetch all data only if dirty bit is set
on 'cursor up'