Added NzBuffer::SetStorage

Fixed (Index/Vertex)Buffer::(Fill/Map) not filling/mapping the entire
buffer when the third argument was zero
Fixed Renderer not accepting sequential index buffer

include/Nazara/Utility/Buffer.hpp

@@ -76,6 +76,9 @@ class NAZARA_API NzBuffer : public NzResource, NzNonCopyable
 		bool IsValid() const;
 
 		void* Map(nzBufferAccess access, unsigned int offset = 0, unsigned int length = 0);
+
+		bool SetStorage(nzBufferStorage storage);
+
 		bool Unmap();
 
 		static bool IsSupported(nzBufferStorage storage);