Break up bp-groups-template.php into smaller files.

[tw2113]

Right now, we have four classes and related template functions all defined in one 7000+ line file.

The classes are:
BP_Groups_Template
BP_Groups_Group_Members_Template
BP_Groups_Membership_Requests_Template
BP_Groups_Invite_Template

Logically, I think we could break them up into files based on what the class is related to and include functions that use those class globals. Any functions in the file that don't directly related to a class can remain.

[DJPaul]

Yep. We already have a ticket: #6452

[tw2113]

Explains why I didn't find that ticket. Wasn't quite generic enough in my searching. :D