Don't be case sensitive to attribute names. Handle padded entities when...

Don't be case sensitive to attribute names.  Handle padded entities when checking for bad protocols.  Normalize entities before checking for bad protocols in esc_url(). Props Mauro Gentile, duck_, miqrogroove

git-svn-id: https://core.svn.wordpress.org/trunk@17171 1a063a9b-81f0-0310-95a4-ce76da25c4cd