Bring some order in BP extension settings file
Fix group membership detection in case of the main VGSR group
Fix plugin action links logic

For both the single and network context. Introduces
`vgsr_is_network_context()` to return a boolean on whether the plugin is
activated for the network. This sets the vgsr()->network class global when
called first.
Remove the new `vgsr_is_network_context()`

Since VGSR is a Network Only plugin, considering the network context can be done by just evaluating whether this is a multisite install.
Update logic and docblocks in user/functions.php