change blockchain -> block chain (spelling)

- Wiki says "block chain" is correct ;)
- remove some unneeded spaces I found in the source, while fixing the spelling

src/main.h

@@ -777,7 +777,7 @@ public:
     // unspent transaction outputs; spent outputs are .IsNull(); spent outputs at the end of the array are dropped
     std::vector<CTxOut> vout;
 
-    // at which height this transaction was included in the active blockchain
+    // at which height this transaction was included in the active block chain
     int nHeight;
 
     // version of the CTransaction; accesses to this value should probably check for nHeight as well,
@@ -798,7 +798,7 @@ public:
 
     // equality test
     friend bool operator==(const CCoins &a, const CCoins &b) {
-         return a.fCoinBase == b.fCoinBase && 
+         return a.fCoinBase == b.fCoinBase &&
                 a.nHeight == b.nHeight &&
                 a.nVersion == b.nVersion &&
                 a.vout == b.vout;