Add test for empty elsif branch

This used to work in `v0.26.1`.
Support empty elsif in MultilineIfThen

And simplify a lot. Closes #1433.
Merge pull request #1438 from jonas054/1433_MultilineIfThen

Support empty elsif in MultilineIfThen
Add test for empty elsif branch

This used to work in `v0.26.1`.
Support empty elsif in MultilineIfThen

And simplify a lot. Closes #1433.
Merge remote-tracking branch 'upstream/master'
Update a few messages to match the wording used in the style guide
[Fix #1406] Allow a newline in SpaceInsideRangeLiteral
Cut 0.27.1
Merge remote-tracking branch 'upstream/master'