Add a11y state tests

This adds a new test which can be scripted to trigger various
event and action sequences, and record state changes in the
accessibility layer.

So far, there are a few tests verifying state changes when
focus changes.

Related to https://bugzilla.gnome.org/show_bug.cgi?id=715176

testsuite/a11y/Makefile.am

@@ -1,6 +1,8 @@
 include $(top_srcdir)/Makefile.decl
 NULL =
 
+SUBDIRS = state
+
 check_PROGRAMS = $(TEST_PROGS)
 
 AM_CPPFLAGS =				\
@@ -39,11 +41,6 @@ TEST_PROGS += value
 
 TEST_PROGS += misc
 
-# the focus test has no chance of working until
-# all the idle handlers in gail are gone
-#
-# TEST_PROGS += focus
-
 TEST_PROGS += tree-relationships
 
 TEST_PROGS += util