Changes

Changes from Mercurial (hg https://isabelle.in.tum.de/repos/isabelle/ default)

Changeset 80400:898034c8a799 by paulson _lp15@cam.ac.uk_: Tidied some messy proofs
The file was modified	`src/HOL/Algebra/Group.thy`
The file was modified	`src/HOL/Algebra/Sylow.thy`