Data: avoid non-alphanumeric chars in expando properties

Ref chromium issue 378607
Ref #14839
Closes gh-1662
README: Improve build instructions

Thanks @NickStefan

Closes gh-1663
Merge remote-tracking branch 'remotes/jquery-original/master'
fix jquery.js test loader code such that stand-alone tests, e.g. /test/hovertest.html can execute.
Merge branch 'fix-delegate-mouseover-problem'

Conflicts:
	test/jquery.js