* eat.el (eat--get-shell-history): New argument FORMAT, pass it
to 'eat--prompt-populate-input-ring'.
* eat.el (eat--handle-uic): Accept FORMAT argument in input
history reporting sequence and pass it to
'eat--get-shell-history'.
* eat.el (eat--prompt-populate-input-ring): New argument
FORMAT. Support Zsh extended history file format.
* integration/bash (__eat_enable_integration): Send "bash" as
the history file format.
* integration/zsh (__eat_enable_integration): Send shell
history.
