Measurement of relative oscillator strengths for Ni I. Transitions from levels $a^3F_{4-2}(0.00-0.27\enspace\text {eV}), a^3D_{3-1}(0.03-0.21\enspace\text {eV})\enspace\text {and}\enspace a^1D_2(0.42\enspace\text {eV})$