Commit 2021-01-14 11:59 3b3f9a21

refactor(measure_theory): review def&API of the dirac measure (#5732)

• use set.indicator instead of ⨆ a ∈ s, 1 in the definition.
• rename some theorems to thm', add a version assuming [measurable_singleton_class α] but not is_measurable s/measurable f under the old name.
• rename some lemmas from eventually to ae.