new doc and optical backprop

tests/recurrent_perf.cpp

@@ -0,0 +1,12 @@
+#include <NeuralNetwork/Recurrent/Network.h>
+
+#include <assert.h>
+#include <iostream>
+
+int main() {
+	NeuralNetwork::Recurrent::Network a(2,1,1000);
+
+	for(size_t i=0;i<10000;i++) {
+		 a.computeOutput({1,0.7});
+	}
+}