Handle operators in haskell-ident-pos-at-point too

[geraldus]

Let's see will it pass the tests. I think I can add some tests for operators too.

[geraldus]

And it turns that we can drop haskell-completions-general-prefix due to prefix grabber no longer handles comments and strings (this will be next PR).

[geraldus]

Don't merge this yet, this implementation is buggy :(

[gracjan]

I think this function should be compatible with thing-at-point. That one seems to be standard.

[geraldus]

@gracjan I agree, but not this time, ok? (:

[coveralls]

Coverage increased (+0.4%) to 30.248% when pulling 93e0111 on geraldus:g/fix-1213 into cc22219 on haskell:master.

[geraldus]

@gracjan please review.

[gracjan]

Looks good to me. Lets wait the usual two days so that other people may look at the code.

[geraldus]

@gracjan no one going to test this 😌

[gracjan]

Merged.