mathlib3

9f17db51 - feat(analysis/special_functions/integrals): mul/div by a const (#6357)

feat(analysis/special_functions/integrals): mul/div by a const (#6357) This PR, together with #6216, makes the following possible: ``` import analysis.special_functions.integrals open real interval_integral open_locale real example : ∫ x in 0..π, 2 * sin x = 4 := by norm_num example : ∫ x:ℝ in 4..5, x * 2 = 9 := by norm_num example : ∫ x in 0..π/2, cos x / 2 = 1 / 2 := by simp ```