fixed map bugfix (fist instead of first), new access functions for fixed maP

(first(), second()), some documentation, raw pool access read() call public
because call is necessary before using public serialize function.
maybe integrate read() call into serialize function?

serialize/SerialArrayListAdapter.h

@@ -27,6 +27,7 @@ public:
 
 	static ReturnValue_t serialize(const ArrayList<T, count_t>* list, uint8_t** buffer, uint32_t* size,
 			const uint32_t max_size, bool bigEndian) {
+		// Serialize length field first
 		ReturnValue_t result = SerializeAdapter<count_t>::serialize(&list->size,
 				buffer, size, max_size, bigEndian);
 		count_t i = 0;