Ctrl + K - add some productivity :)

Hello,

I find this patch make more convenient (un)commenting lines in sql
editor and I think such behavior is much more like other IDE's.

1. When press Ctrl + K on a selected text: If a selected text ends
with '\n' then a comment after it is not added.
2. If there is no selection: comment a several lines by pressing Ctrl
+ K repeatedly.

Can you apply it to official release?
(1) fixes some unintuitive behavior
With (2) you can quickly (un)comment several lines (no need to select
a line with mouse or keyboard etc - just press Ctrl + K)

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Best regards,
Nail Samatov