A pair of strong earnings reports sent staffing firms Manpower (MAN) and Robert Half International (RHI) soaring. Manpower closed up almost 10% at 39.53. Robert Half was up 5% at 27.24. Employers are still wary of hiring in the weak economy. But job prospects have picked up, and both reported stronger outlooks in niches they serve. Both also forecast higher fourth-quarter earnings. Manpower said third-quarter earnings per share slipped 19% to 79