Support for traits has been added.
Short array syntax has been added, e.g. $a = [1, 2, 3, 4]; or $a = ['one' => 1, 'two' => 2, 'three' => 3, 'four' => 4];.
Function array dereferencing has been added, e.g. foo()[0].
Closures now support $this.
<?= is now always available...