New features release

This release contains the following main items

91b3550 : Add extension hook after re-ordering items
8e56ed3 : Add tests for 3 and 3.2 branches, support 5.6 Rename relations which are now physical methods in 3.2
b6056fc : add support for setting a default value for GridFieldAddNewMultiClasss
4c8009a : Adding possibility to define a custom text for the link
9a253f2 : using hasmethod instead of method_exists
8a9e075 : Allowing to refer to external links from a modeladmin
f57278b : BUG Ensure that sorting a row doesn't destroy any unsaved inline changes

Along with additional formatting and whitespace fixes