Bitcoin-Qt: never display own block count > estimated block count

- some users reported it as weird, that the estimated block count could be
  lower than our own nodes block number (which is indeed true and not good)
- this pull adds a new default behaviour, which displays our own block
  number as estimated block number, if own >= est. block count
- the pull raises space for nodes block counts in cPeerBlockCounts to 8 to
  be more accurate
- also removes a reduntant setNumBlocks() call in RPCConsole and moves
  initialisation of numBlocksAtStartup in ClientModel, where it belongs

src/main.cpp

@@ -45,7 +45,7 @@ bool fReindex = false;
 bool fBenchmark = false;
 unsigned int nCoinCacheSize = 5000;
 
-CMedianFilter<int> cPeerBlockCounts(5, 0); // Amount of blocks that other nodes claim to have
+CMedianFilter<int> cPeerBlockCounts(8, 0); // Amount of blocks that other nodes claim to have
 
 map<uint256, CBlock*> mapOrphanBlocks;
 multimap<uint256, CBlock*> mapOrphanBlocksByPrev;