Clean up threading

* Rename everything.
    * Strip J prefix.
    * Change UpperCamelCase functions to lowerCamelCase.
  * Remove global (!) semaphore count mutex on OSX.
  * Remove semaphore count getter (unused, unsafe, depended on internal
    API functions on Windows, and used a hack on OSX).
  * Add `Atomic<type>`.
  * Make `Thread` handle thread names.
  * Add support for C++11 multi-threading.
  * Combine pthread and win32 sources.
  * Remove `ThreadStarted` (unused, unneeded).
  * Move some includes from the headers to the sources.
  * Move all of `Event` into its header (allows inlining with no new includes).
  * Make `Event` use `Semaphore` (except on Windows).
  * Move some porting functions into `Thread`.
  * Integrate logging with `Thread`.
  * Add threading test.

src/util/numeric.h

@@ -24,7 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "../irr_v2d.h"
 #include "../irr_v3d.h"
 #include "../irr_aabb3d.h"
-#include "../jthread/jmutex.h"
+#include "../threading/mutex.h"
 #include <list>
 #include <map>
 #include <vector>
@@ -42,7 +42,7 @@ class FacePositionCache
 private:
 	static void generateFacePosition(u16 d);
 	static std::map<u16, std::vector<v3s16> > m_cache;
-	static JMutex m_cache_mutex;
+	static Mutex m_cache_mutex;
 };
 
 class IndentationRaiser