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/timedata.h

@@ -1,5 +1,5 @@
 // Copyright (c) 2014 The Bitcoin developers
-// Distributed under the MIT/X11 software license, see the accompanying
+// Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_TIMEDATA_H
@@ -12,7 +12,8 @@
 
 class CNetAddr;
 
-/** Median filter over a stream of values.
+/** 
+ * Median filter over a stream of values.
  * Returns the median of the last N numbers
  */
 template <typename T>
@@ -67,7 +68,7 @@ public:
     }
 };
 
-/* Functions to keep track of adjusted P2P time */
+/** Functions to keep track of adjusted P2P time */
 int64_t GetTimeOffset();
 int64_t GetAdjustedTime();
 void AddTimeData(const CNetAddr& ip, int64_t nTime);