Convert remaining comments in /src to doxygen format

- Update comments in checkpoints to be doxygen compatible
- Update comments in checkqueue to be doxygen compatible
- Update coins to be doxygen compatible
- Fix comment typo in crypter.h
- Update licenses/copyright dates

Closes #5325 #5184 #5183 #5182

src/coins.cpp

@@ -1,5 +1,5 @@
-// Copyright (c) 2012-2013 The Bitcoin developers
-// Distributed under the MIT/X11 software license, see the accompanying
+// Copyright (c) 2012-2014 The Bitcoin developers
+// Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "coins.h"
@@ -8,9 +8,11 @@
 
 #include <assert.h>
 
-// calculate number of bytes for the bitmask, and its number of non-zero bytes
-// each bit in the bitmask represents the availability of one output, but the
-// availabilities of the first two outputs are encoded separately
+/**
+ * calculate number of bytes for the bitmask, and its number of non-zero bytes
+ * each bit in the bitmask represents the availability of one output, but the
+ * availabilities of the first two outputs are encoded separately
+ */
 void CCoins::CalcMaskSize(unsigned int &nBytes, unsigned int &nNonzeroBytes) const {
     unsigned int nLastUsedByte = 0;
     for (unsigned int b = 0; 2+b*8 < vout.size(); b++) {
@@ -133,7 +135,7 @@ const CCoins* CCoinsViewCache::AccessCoins(const uint256 &txid) const {
 bool CCoinsViewCache::HaveCoins(const uint256 &txid) const {
     CCoinsMap::const_iterator it = FetchCoins(txid);
     // We're using vtx.empty() instead of IsPruned here for performance reasons,
-    // as we only care about the case where an transaction was replaced entirely
+    // as we only care about the case where a transaction was replaced entirely
     // in a reorganization (which wipes vout entirely, as opposed to spending
     // which just cleans individual outputs).
     return (it != cacheCoins.end() && !it->second.coins.vout.empty());