General tidy and refactoring:

* Use nullptr (C++11) instead of NULL.
* Put each file into its own namespace declaration.
* Remove "using namespace" directives and add scope qualifiers.
* Control when beast's implementation of std::equal (C++14) is used.
* Tidy up some const declarations.

Conflicts:
	src/ripple_app/shamap/SHAMapSync.cpp
	src/ripple_app/tx/TransactionEngine.cpp

src/ripple/http/impl/ServerImpl.cpp

@@ -20,7 +20,7 @@
 namespace ripple {
 namespace HTTP {
 
-ServerImpl::ServerImpl (Server& server, Handler& handler, Journal journal)
+ServerImpl::ServerImpl (Server& server, Handler& handler, beast::Journal journal)
     : Thread ("HTTP::Server")
     , m_server (server)
     , m_handler (handler)
@@ -37,7 +37,7 @@ ServerImpl::~ServerImpl ()
     stopThread ();
 }
 
-Journal const& ServerImpl::journal() const
+beast::Journal const& ServerImpl::journal() const
 {
     return m_journal;
 }