Make haskell-process-do-info prompt on prefix arg.

@hvr FYI
Add haskell-presentation-mode and option.

@hvr might be of interest.
Support popups from popups.
Forgot that this function is used in contextual-space.
Move session assigning to haskell-process.

@hvr this avoids the dependency problem.
Woops, forgot this part.

@hvr