Tidying

Change-Id: I6e8c8bee3664c5cd9975fce3cf1a3b3670e4cca2
Reviewed-on: http://gerrit.dmdirc.com/3864
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Rename TabCompleterResult.

It's not a result of completing, it's a collection of matches after
starting completion.

Move logic specifically for the bash tab completer into the bash
plugin.

Change-Id: I24dfd19a887a4bafe767aa24377d6dbeb305f77d
Reviewed-on: http://gerrit.dmdirc.com/3866
Reviewed-by: Greg Holmes <greg@dmdirc.com>
Automatic-Compile: DMDirc Build Manager