Should suppress widgets and links for disabled plugins #677

Reported by kaystrobach in comment:ticket:551:3:

it's the same for feedback, dashboard, api, ... -> all are hardcoded ... :(, if seen this after deeactivating the feedbackplugin

• deactivating a plugin does not currently suppress/remove associated widgets from the dashboard; however, the dashboard will still try to load the widgets; we should suppress if deactivated, and remove if the plugin is uninstalled

Duped by #999. See navbar patch.

@vipsoft:
Are there other ocurrences of these links other than in the uppermost navigation? (for these i submitted a patch #999)

I'll commit your patch for #999 separately.

The other half of this ticket is to suppress a disabled plugin's widgets in the dashboard layout.

In [1486], fixes #999, refs #677 - suppress top bar nav links for disabled plugins

in [1599](why did the trac not automatically put the message here?)

note that if ones disables all plugins, then go to the dashboard, adds a widget, all previously added widgets from disabled plugins will then be lost on dashboard layout save.