Sessionable shell history

[lmorg]

The history writer is just a stdio interface so add a config option to alter the history endpoint.

[lmorg]

To redirect shell history:

pipe: --create foo --file bar.txt
history-set-write-pipe: foo

Because it is a standard murex named pipe, you can also use other writers. eg

pipe: --create foo --tcp-dial localhost:8000
history-set-write-pipe: foo

...or even disable history logging entirely using the builtin null pipe

history-set-write-pipe: null