Added empty lines to the Doxygen comments in the constructor header.

Last commit of this file modified the comments so that the Doxygen
output included blank lines.  This change has added blank lines to
the "source" comments in the file.

src/lib/log/logger.h

@@ -49,6 +49,7 @@ public:
     /// \param name Name of the logger.  If the name is that of the root name,
     /// this creates an instance of the root logger; otherwise it creates a
     /// child of the root logger.
+    ///
     /// \param exit_delete This argument is present to get round a bug in
     /// log4cxx.  If a log4cxx logger is declared outside an execution unit, it
     /// is not deleted until the program runs down.  At that point all such
@@ -57,7 +58,8 @@ public:
     /// destroyed causes a MutexException to be thrown (this is described in
     /// https://issues.apache.org/jira/browse/LOGCXX-322).  As this only occurs
     /// during program rundown, the issue is not serious - it just looks bad to
-    /// have the program crash instead of shut down cleanly.\n\n
+    /// have the program crash instead of shut down cleanly.\n
+    /// \n
     /// The original implementation of the isc::log::Logger had as a member a
     /// log4cxx logger (actually a LoggerPtr).  If the isc:: Logger was declared
     /// statically, when it was destroyed at the end of the program the internal
@@ -65,7 +67,8 @@ public:
     /// not occur if the isc::log::Logger was created on the stack.  To get
     /// round this, the internal LoggerPtr is now created dynamically.  The
     /// exit_delete argument controls its destruction: if true, it is destroyed
-    /// in the ISC Logger destructor.  If false, it is not.\n\n
+    /// in the ISC Logger destructor.  If false, it is not.\n
+    /// \n
     /// When creating an isc::log::Logger on the stack, the argument should be
     /// false (the default); when the Logger is destroyed, all the internal
     /// log4cxx objects are destroyed.  As only the logger (and not the internal