Specified base_uint component size

A base_uint used to be made of an array of unsigned ints. This works
fine on most platforms, but might not work on certain present or future
platforms. The code breaks if an unsigned int is 16 or 64 bits, so it's
important to be specific. Also changed "u" to "you".

src/uint256.h

@@ -8,6 +8,7 @@
 #include <limits.h>
 #include <stdio.h>
 #include <string.h>
+#include <inttypes.h>
 #include <string>
 #include <vector>
 
@@ -20,14 +21,14 @@ inline int Testuint256AdHoc(std::vector<std::string> vArg);
 
 
 /** Base class without constructors for uint256 and uint160.
- * This makes the compiler let u use it in a union.
+ * This makes the compiler let you use it in a union.
  */
 template<unsigned int BITS>
 class base_uint
 {
 protected:
     enum { WIDTH=BITS/32 };
-    unsigned int pn[WIDTH];
+    uint32_t pn[WIDTH];
 public:
 
     bool operator!() const