Squashed 'lib/select2/' changes from b8fa72d..55aa184

55aa184 Merge pull request #1987 from 76200/patch-1
92103a8 Merge pull request #2002 from justbeez/master
a44cf9f Merge pull request #2003 from jdecuyper/feature-next-search-term-multiple
29b88e3 Merge pull request #2006 from robertfausk/patch-1
1218a35 Add integration for symfony2
c7dd8c5 Enable nextSearchTerm function for multiple select
8a56045 Fix CSS linear-gradient syntax
29d3d12 Fixed plural suffix for Polish translation

git-subtree-dir: lib/select2
git-subtree-split: 55aa184c316abab26324b51ddd85a271ebb76864
Merge commit '79583cd91477280a978d4011c624c7798f4bbd08'
style