I (finally) found some time and included an absolute minimal
proof-of-concept App that uses the Framework: MinimalMacVim target in
the Xcode project. Basically it has one class
(MinimalMacVim/MMAppDelegate.m) which is the delegate for everything.
And for the sake of simplicity it does not handle many things like
resizing the Vim-view properly when a new tab is created.
Over the course of time I'll try to improve the Framework and make it
easier to use. (Eg, some delegate methods should/can be handled
Maybe some other folks will find the Framework useful..