Issues with service utils.kde

[thehrh]

• general problem running in single-precision FP mode? (pisa_tests/test_kde_stage.py fails with Error: lists contain a non-float value)
• but pisa_tests/test_kde_stage.py also fails to assert np.abs(total_no_lin / total_with_lin - 1.0) < 0.05 in double-precision mode