FYI: tests reorg in sources

[Benjamin Otte <otte gnome org>]

Hey,

As part of the installed-tests work in master I've moved all tests into a new
  testsuite/
directory in the sources toplevel directory.

In particular, these directories moved:
  gdk/tests => testsuite/gdk
  gtk/tests => testsuite/gtk
  tests/a11y => testsuite/a11y
  tests/css => testsuite/css
  tests/reftests => testsuite/reftests

In the future, please put all automated tests into the right
testsuite/ subdirectory and do not put anything not related to
automated tests there.
The tests/ subdirectory will continue to be the place for interactive
testing apps that aren't installed.

Benjamin