Improve history navigation in haskell-interactive-mode

[hvr]

Basically, make haskell-interactive-mode behave more like other existing interactive modes such as eshell-mode or comint-mode (from which many other modes are derived).

[hvr]

More possible improvements:

• Temporarily store the current expression at the prompt before navigating history (see how comint behaves in e.g. M-x ielm) and allow the expression to be restored.
• Provide pattern-based history search (see comint/eshell)
• Support for setting/limiting maximum history size
• Maybe switch to use ring.el as data structure for the history