trac #14581: GLPK incorrectly handles zero bounds
Added rewriting systems for finitely presented groups.
Added rewriting systems of finitely presented groups
Move checks from prereq.sh to configure
Merge branch 'ticket/15580' into ticket/15606

Conflicts:
	configure.ac
Revert changes to sage-update-version
Symlink config.log to logs/pkgs/config.log
sanitize write permissions before creating tarballs
Merge branch 'u/jdemeyer/ticket/15580' of git://trac.sagemath.org/sage into ticket/15606

Conflicts:
	build/prereq.sh
	configure.ac
Merge branch 'u/mmarco/ticket/15528' of trac.sagemath.org:sage into u/tscrim/ticket/15528
Merge remote-tracking branch 'origin/develop' into ticket/15675

Conflicts:
	src/bin/sage-sdist
Set tarball permissions to go=rX
Move all bootstrapping to ./bootstrap
Merge branch 'develop' of trac.sagemath.org:sage into u/tscrim/ticket/15528
Review changes for #15528.
Made the repr sorted for the rules.
Added  free_group and finitely_presented_group
Do not use the GNU extension chmod --recursive
LinearMatroid.is_field_equivalent now tests if self is other before calling LinearMatroid._is_field_isomorphism.
Trac #15675: Sanitize source tarball permissions

Files in sdist/bdist tarballs should have permissions either 0644 or
0755, nothing else.

URL: http://trac.sagemath.org/15675
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): Jeroen Demeyer