haskell-process-suggest-remove-import leaves blank line rather than completely remove it

[geraldus]

Current implementation of haskell-suggest-remove-import just clears line contents but do not removes it when user answers y. I propose to remove entire line, e.g.

import A
import D -- ^ this import is redundant
import B

-- current behavior
import A

import B

-- proposed
import A
import B

[gracjan]

@geraldus, @chrisdone: reopened.

[geraldus]

It was decided to delay this until some infrastructure improvements will be done.

[geraldus]

Step 1 in direction proposed by Gracjan could be:

1. introduce some global suggestions / info stack
2. do not prompt user during file loading, package building, rather collect all info from compiler output to stack.
3. ignore / mark as irrelevant messages for visited files if buffer have modified (unsaved) state.

Until overlay infrastructure is not ready:
4. after loading finished either process suggestion stack immediately or inform user to run special command.

When overlay infrastructure will be ready, we can substitute step 4.

@gracjan what do you think?

[gracjan]

I'm okay with this plan.