updated dashicons font declaration and font files

git-svn-id: https://plugins.svn.wordpress.org/mp6/trunk@745355 b8457f37-d9ea-0310-8a92-e5e31aec5664
merged changesets 24761, 24768, 24769, 24770 and 24775 from core

git-svn-id: https://plugins.svn.wordpress.org/mp6/trunk@745356 b8457f37-d9ea-0310-8a92-e5e31aec5664