Feature/life safety zone object example (#595)

* Added Keylist_Data_Free function to free all nodes and data in a list

* Added basic Life Safety Zone object type in the apps/server example, with unit testing.

src/bacnet/basic/sys/keylist.h

@@ -87,6 +87,11 @@ extern "C" {
     void *Keylist_Data_Pop(
         OS_Keylist list);
 
+/* removes and frees all data from the list */
+    BACNET_STACK_EXPORT
+    void Keylist_Data_Free(
+        OS_Keylist list);
+
 /* returns the data from the node specified by key */
     BACNET_STACK_EXPORT
     void *Keylist_Data(
@@ -115,8 +120,8 @@ extern "C" {
 /* returns the node key specified by the index */
     BACNET_STACK_EXPORT
     bool Keylist_Index_Key(
-        OS_Keylist list, 
-        int index, 
+        OS_Keylist list,
+        int index,
         KEY *pKey);
 
 /* returns the next empty key from the list */