Trac #14882: typos in backtrack.py
Trac #14838: correct link to cvxopt documentation
Trac #13857: symbolic minmax commentary
Trac #13857: reviewer patch
#14985: Let zlib 1.2.>=7 build on Cygwin.
#15001: Update to prerelease 1.1pre9.
Trac #15019: Fixing differentiation
5.11.rc1
5.11.rc1
Merge 'sage-5.11.rc1' into master