vl_covdet.c: signal better the duplication of features when ambiguous orientations are detected
vl_covdet.c: signal better the duplication of features when ambiguous orientations are detected

Resolves: #20

vlfeat/vlfeat,erexhepa/vlfeat,qubick/vlfeat,hongzhili/vlfeat,hongzhili/vlfeat,CansenJIANG/vlfeat,erexhepa/vlfeat,WangDequan/vlfeat,j-bo/vlfeat,rxl194/vlfeat,WangDequan/vlfeat,mylxiaoyi/vlfeat,WangDequan/vlfeat,vlfeat/vlfeat,cvfish/vlfeat,erexhepa/vlfeat,hongzhili/vlfeat,CansenJIANG/vlfeat,qubick/vlfeat,CansenJIANG/vlfeat,WangDequan/vlfeat,rxl194/vlfeat,qubick/vlfeat,erexhepa/vlfeat,richarddzh/vlfeat,mylxiaoyi/vlfeat,WangDequan/vlfeat,hongzhili/vlfeat,richarddzh/vlfeat,qubick/vlfeat,mylxiaoyi/vlfeat,mylxiaoyi/vlfeat,cvfish/vlfeat,qubick/vlfeat,j-bo/vlfeat,j-bo/vlfeat,cvfish/vlfeat,cvfish/vlfeat,rxl194/vlfeat,vlfeat/vlfeat,vlfeat/vlfeat,WangDequan/vlfeat,rxl194/vlfeat,rxl194/vlfeat,CansenJIANG/vlfeat,qubick/vlfeat,hongzhili/vlfeat,richarddzh/vlfeat,CansenJIANG/vlfeat,vlfeat/vlfeat,erexhepa/vlfeat,richarddzh/vlfeat,erexhepa/vlfeat,rxl194/vlfeat,mylxiaoyi/vlfeat,richarddzh/vlfeat,vlfeat/vlfeat,hongzhili/vlfeat,cvfish/vlfeat,j-bo/vlfeat,richarddzh/vlfeat,CansenJIANG/vlfeat,cvfish/vlfeat,mylxiaoyi/vlfeat,j-bo/vlfeat