Open link in same tab in Twitch Channels widget

[sysmiguel]

Description

When clicking on each channel they get opened in a seperate tab. With this feature someone could add the same-tab configuration key (similar to the bookmarks widget) to make the links open in the same tab.

The widget title would open in a seperate tab, because this it is defined in the widgetBase and not in the specific twitch widget. Also fine granularity similar to the bookmarks would not work with the current way channels are being configured.

I would happily implement this feature in a basic way that does not cause backwards incompability and does not mess with the current widgetBase.