Ensure that the old translator is not used after calling espeak_Terminate.

src/libespeak-ng/speech.c

 	outbuf = NULL;
 	FreePhData();
 	FreeVoiceList();
+	translator = NULL;
 
 	return ENS_OK;
 }

tests/api.c

 	printf("testing espeak_Terminate without espeak_Initialize\n");
 
 	assert(event_list == NULL);
+	assert(translator == NULL);
 
 	assert(espeak_Terminate() == EE_OK);
 	assert(event_list == NULL);
+	assert(translator == NULL);
 }
 
 void
 	printf("testing espeak_Initialize\n");
 
 	assert(event_list == NULL);
+	assert(translator == NULL);
 
 	assert(espeak_Initialize(AUDIO_OUTPUT_PLAYBACK, 0, NULL, 0) == 22050);
 	assert(event_list != NULL);
+	assert(translator == NULL);
 
 	assert(espeak_Terminate() == EE_OK);
 	assert(event_list == NULL);
+	assert(translator == NULL);
 }
 
 void
 	printf("testing espeak_Synth\n");
 
 	assert(event_list == NULL);
+	assert(translator == NULL);
 
 	assert(espeak_Initialize(AUDIO_OUTPUT_RETRIEVAL, 0, NULL, 0) == 22050);
 	assert(event_list != NULL);
+	assert(translator == NULL);
 
 	const char *test = "One two three.";
 	assert(espeak_Synth(test, strlen(test)+1, 0, POS_CHARACTER, 0, espeakCHARS_AUTO, NULL, NULL) == EE_OK);
+	assert(translator != NULL);
+
 	assert(espeak_Synchronize() == EE_OK);
+	assert(translator != NULL);
 
 	assert(espeak_Terminate() == EE_OK);
 	assert(event_list == NULL);
+	assert(translator == NULL);
 }
 
 int
 	test_espeak_initialize();
 
 	test_espeak_synth();
+	test_espeak_synth(); // Check that this does not crash when run a second time.
 
 	return EXIT_SUCCESS;
 }