message: made some C++ API methods const
diff: @@ -107,14 +107,14 @@ OIDN_NAMESPACE_BEGIN
  // Maps a region of the buffer to host memory.
  // If byteSize is 0, the maximum available amount of memory will be mapped.
  - void* map(Access access = Access::ReadWrite, size_t byteOffset = 0, size_t byteSize = 0)
  + void* map(Access access = Access::ReadWrite, size_t byteOffset = 0, size_t byteSize = 0) const
  {
  return oidnMapBuffer(handle, (OIDNAccess)access, byteOffset, byteSize);
  }
  // Unmaps a region of the buffer.
  // mappedPtr must be a pointer returned by a previous call to map.
  - void unmap(void* mappedPtr)
  + void unmap(void* mappedPtr) const
  {
  oidnUnmapBuffer(handle, mappedPtr);
  }
  @@ -458,19 +458,19 @@ OIDN_NAMESPACE_BEGIN
  }
  // Creates a new buffer (data allocated and owned by the device).
  - BufferRef newBuffer(size_t byteSize)
  + BufferRef newBuffer(size_t byteSize) const
  {
  return oidnNewBuffer(handle, byteSize);
  }
  // Creates a new shared buffer (data allocated and owned by the user).
  - BufferRef newBuffer(void* ptr, size_t byteSize)
  + BufferRef newBuffer(void* ptr, size_t byteSize) const
  {
  return oidnNewSharedBuffer(handle, ptr, byteSize);
  }
  // Creates a new filter of the specified type (e.g. "RT").
  - FilterRef newFilter(const char* type)
  + FilterRef newFilter(const char* type) const
  {
  return oidnNewFilter(handle, type);
  }
  