ensure clean and consistent "namespace" usage

- remove some missplaced ;
- ensure end of a namespace is clearly visible
- use same formatting when using namespace

src/checkpoints.h

@@ -13,8 +13,8 @@ class uint256;
 /** Block-chain checkpoints are compiled-in sanity checks.
  * They are updated every release or three.
  */
-namespace Checkpoints
-{
+namespace Checkpoints {
+
     // Returns true if block passes checkpoint checks
     bool CheckBlock(int nHeight, const uint256& hash);
 
@@ -27,6 +27,7 @@ namespace Checkpoints
     double GuessVerificationProgress(CBlockIndex *pindex, bool fSigchecks = true);
 
     extern bool fEnabled;
-}
+
+} //namespace Checkpoints
 
 #endif