update .gitignore to ignore objects in their directory

.gitignore

src/objects/Commons.o

src/objects/Configuration.o

src/objects/Parsers.o

src/objects/cfrfme.o

src/objects/clffft.o

src/objects/clu.o

src/objects/clu_subs.o

src/objects/cluster.o

src/objects/edfb_clu.o

src/objects/edfb_sph.o

src/objects/file_io.o

src/objects/frfme.o

src/objects/lffft.o

src/objects/np_cluster.o

src/objects/np_sphere.o

src/objects/np_trapping.o

src/objects/sph.o

src/objects/sph_subs.o

src/objects/sphere.o