Prevent intellisense suggestions and auto imports when writing comments

Right now, when you refer to a library in comments, `Data.Either` for instance, the extension auto suggests importing that library and imports it automatically if you press enter. It also kicks into action if you start your comment with `>>>`.

IMO, it would be better if the extension would avoid automatic activity when we are writing comments and only do so on specific request (by pressing `ctrl+space` for example).