Fixed classes with undefined constructor.

IterativeRobot and BinaryImage had no constructor
defined (and so would give linker errors).
Error just had an empty constructor defined,
so I switched to "=default".

Change-Id: Ia8efb4282928227878dfefeda58ccb8cf06aabb2

wpilibc/wpilibC++/src/Error.cpp

@@ -17,8 +17,6 @@
 #include "Timer.h"
 #include "Utility.h"
 
-Error::Error() {}
-
 void Error::Clone(const Error& error) {
   m_code = error.m_code;
   m_message = error.m_message;