Navigating grouped candidates using arrow keys is broken

[mattirn]

Navigating grouped command candidates is broken. There are also other problems if the grouped candidates do not fit to the terminal display.

Example: From the initial position BYTES pressing once the left arrow key selected candidate moves to toHexString

Solution: Grouping of the candidates is removed when starting to navigate candidates.

[bdw429s]

This was the wrong solution to just remove functionality instead of fixing it. Please restore the missing and useful functionality of candidate grouping.

See: #613

And if JLine follows semantic versioning, it was also incorrect to introduce a breaking change into a minor release.