Hi Martin,
10.2 is pretty old, the actual version is 10.5. Things would be much easier for you if you would at least move to 10.4.
I used libraries with 10.3, and the following posts might help you to do the same thing with 10.2 (but not sure as I moved up to post 10.2 long time ago):
http://mcuoneclipse.com/2012/10/08/a-library-with-arm-gcc-and-eclipse/
Creating and using Libraries with ARM gcc and Eclipse | MCU on Eclipse
I hope this helps.