<TAB> key press inserts '\t' character in code editor as indentation.

[onesimus-wiafe]

I have reopened this PR after #2747 for issue #2703.

1. On the TAB key press, \t is inserted into the caret's position.
2. There is a test to confirm the behavior.

[texodus]

Thanks for the PR!

Can you please rebase this on master branch and remove the file results.tar.gz from commit 7ca2860 ? I've rebased your branch with the changes here which you can copy, or if you don't care about the PR attribution I can cherry-pick these changes onto a new branch that does not conflict (your commits will still be attributed correctly).

[onesimus-wiafe]

made the changes @texodus