Which directory layout for develoment

[Guyou]

Hi,

Few month ago, I started my first application with GNUStep and
Objective-C. It's a quite good experience, but I miss time to work on
it.

Well.

But, my code grows. So, I wish to create some "package" to organize my
development.
Actually, all my code is in the main directory and compilation is
managed with a single GNUmakefile.

How can I split/organize my source files?
I tried to move some isolated code in a subdirectory and produce a
library, but this lib. is not included in the .app directory. So I
imagine my reorganisation is incorrect.
Is there any documentation around the recommended directory layout for
a GNUStep development?

Any tips concerning layout for organising unit tests is also welcome.

PS: I do not use ProjectCenter or any other GNUStep IDE because:
- my first contact was rude (the pop-up menus opened behind the main
window, so I was unable to click on it;
- GNUStep development is occasionnal, so I prefer to use Eclipse (I
also do C/C++ and Java development).

Regards,
Guyou