Make many more utility classes/headers public. (#76)

Moving these headers from src to include enables other libraries to use the
functionality provided.

* tcpsockets
* atomic_static
* raw_istream
* timestamp
* SafeThread
* Base64
* LEB128
* ConcurrentQueue

The classes have been moved into the wpi namespace as they're generic.

src/RpcServer.h

@@ -15,10 +15,10 @@
 #include <utility>
 
 #include "llvm/DenseMap.h"
-#include "atomic_static.h"
+#include "support/atomic_static.h"
+#include "support/SafeThread.h"
 #include "Message.h"
 #include "ntcore_cpp.h"
-#include "SafeThread.h"
 
 namespace nt {
 
@@ -51,7 +51,7 @@ class RpcServer {
   RpcServer();
 
   class Thread;
-  SafeThreadOwner<Thread> m_owner;
+  wpi::SafeThreadOwner<Thread> m_owner;
 
   struct RpcCall {
     RpcCall(StringRef name_, std::shared_ptr<Message> msg_, RpcCallback func_,