Replace assertions involving calls to in_array() with assertContains()/assertNotContains()

Problem/Motivation

Fox example:

-    $this->assertFalse(in_array('t3', $cids), "Existing key 3 has been removed from &\$cids");
-    $this->assertTrue(in_array('t4', $cids), "Non existing key 4 is still in &\$cids");
+    $this->assertNotContains('t3', $cids);
+    $this->assertContains('t4', $cids);

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet