Run Pyxel with no window
Is there any way to run pyxel in a mode that does not create a window?
Currently i'm running pyxel normally for a game that is 64x64 but for every frame in the draw function, i store the graphics contents as a class variable:
```python
palette = pyxel.colors.to_list() # type: ignore
# transform screen data from color indexes to color hex
pixel_data = [palette[p] for p in pyxel.screen.data_ptr()]  # 64x64 = 4096 pixel data
arr = [[[0,0,0] for _ in range(64)] for _ in range(64)]  # 64x64x3 list
  for i in range(64):
    for j in range(64):
      n = i * 64 + j  # index of pixel in pixel_data
      p = pixel_data[n]  # pixel color reference ex: int 16750488 = hex 0xff9798
                arr[i][j] = [ (p >> 16) & 0xFF, (p >> 8) & 0xFF, p & 0xFF] # create [r, g, b]
self.native_pixel_data = arr  # Store a 64x64x3 Array 
```
Then i load that array with numpy and PIL to create a PIL.Image and show it in a tkinter canvas
```python
# Somewhere in my loop
import numpy, PIL
np_array = numpy.asarray(game.native_pixel_data)  # Parse list as numpy array
img = PIL.Image.fromarray(np_array)
img = ImageTk.PhotoImage(img)  # Convert to image format suitable for tkinter
# Tkinter initialization omitted (create root window and attach Label)
tkinter_panel.configure(image=img)  # Update and display the pyxel frame to tkinter
```

I'm doing this to get the game frame and feed it to a neural network, but also i want to display the current game state in the tkinter window.
