Fix jQuery #13251: use slice instead of substring
(cherry picked from commit 37eb6125c0fb0bec4e0d043bc78110b4f49f3aa6)
Update Sizzle: fixes native slice usage
Fix broken link in CONTRIBUTING.md, close gh-1132.
Fix requirements and dependencies in README, close gh-1131.
Reduced script transport
Further script transport cleanup, close gh-1123.
Consistently clean up after .ready() handler, close gh-1135.
Fix #13232, fix jQuery.buildFragment for tables, close gh-1138.
2.0: Reduce offset module. Close gh-1139.
Fixes #13276. Unit test is enough since the 2.x XHR transport already dismissed the XML as parsed by the XHR instance.
Removes unnecessary call to `.off()` as noted by @dcherman.