fix(frontends/lean/pp): suppress unnecessary '[annotation]' marks
fix(library/tactic/expr_to_tactic): argument evaluation order is not part of the standard
feat(library/tactic): add 'intros' tactic
refactor(library/data/list): minimize dependencies and avoid 'sorry' warning
fix(tests/lean/notation): remove 'sorry' warning from expected outputs
Merge branch 'master' of https://github.com/leanprover/lean