Tab-completion: option to cycle through possible completions

[ssiccha]

Observed behaviour

Currently tab-completion in GAP behaves like this: Pressing tab completes the input partially, if the largest common prefix of all possible completions is longer than the input. If this is not the case the list of all possible completions is shown.

Proposed behaviour

Add maybe a UserPreference such that tab-completion behaves like this: Additionally, after listing all possible completions the user can cycle through them via additional tabs.

This was mentioned both in #919 and the corresponding pull-request #928.

[ssiccha]

I have done some research and readline should in principle be able to do something like that.
E.g. if I add the following lines to my .inputrc and start a new shell it behaves similarly as in the proposal.

Tab: menu-complete
set menu-complete-display-prefix on
set show-all-if-ambiguous on