Changes

Changes from Mercurial (hg https://foss.heptapod.net/isa-afp/afp-devel/ default)

Changeset 13401:f0dfd9de026b by Christian Urban _christian.urban@kcl.ac.uk_: added more simplification rules involving Zero
The file was modified	`thys/Posix-Lexing/Extensions/Simplifying3.thy`
The file was modified	`thys/Posix-Lexing/Simplifying.thy`