- removed bogus assert in buffer code.

An empty buffer is a perfectly valid construct that may not be asserted upon. The 3D scene does not use indices so the buffer receives no data and remains empty.
This made the softpoly renderer fail in debug builds. Performance issues aside it works fine now.

Fixes #314

source/common/rendering/hwrenderer/data/buffers.h

@@ -56,7 +56,7 @@ public:
 	virtual void Resize(size_t newsize) = 0;
 	virtual void Map() {}		// Only needed by old OpenGL but this needs to be in the interface.
 	virtual void Unmap() {}
-	void *Memory() { assert(map); return map; }
+	void *Memory() { return map; }
 	size_t Size() { return buffersize; }
 };