Group context gets lost in child nodes

Hi:

There is a problem with the context in no group pages belonging to a group (child pages).
Now the module is using its own functions to set and get group context (og_galleries_set_context and (og_galleries_get_context) and seems to work inside the module but if you want to use the context in a related module (like og user roles) or to set block visibility inside a group this doen't work.

So I've changed the calls to those functions to calls to the main og functions in og module (og_set_context and og_get_context) and have deleted ther og_galleries function.

This works fine for me and haven't noticed any collateral effect.

I've attached the patch.