use forward decls in protobuf and create static sgproto lib
fix
fix
Add option to build static libshogun
Properly set -fPIC compiler flag if required
The libshogun object set should depend on the bundled libraries
fix fail in FITC when number of latent features is not equal to number of training features
Merge pull request #1757 from votjakovr/feature/gp_refactoring

Fix fail in FITC when number of latent features is not equal to number of training features