Add bash style completion

[blueperspective]

Hi,
This PR features a "bash" style completion :

• if only one suggestion, it is completed
• if more than one suggestion and suggestions are short (15 chars), show all of them in 5 columns
• else show all suggestions, one per line

See attached screenshot.

Regards

[tonerdo]

@blueperspective this feature looks more like suggestions and not completions. It just lists the possible completions but doesn't necessarily complete the text at the prompt. Am I right about this?

[blueperspective]

It does autocomplete if there is only one possibility in the "autocomplete list".
If there is more than one possibility, it is more like suggestions right.