Set min_period default to 0

To preserve delay setting from 1.8 and earlier

Author: Jsfasdf250

TextureAtlas to GIF and Frames.py

@@ -972,7 +972,7 @@ def on_closing():
 loopdelay_entry = tk.Entry(root, textvariable=set_loopdelay)
 loopdelay_entry.pack()
 
-set_minperiod = tk.DoubleVar(value=500)
+set_minperiod = tk.DoubleVar(value=0)
 minperiod_label = tk.Label(root, text="Minimum Period (ms):")
 minperiod_label.pack()
 minperiod_entry = tk.Entry(root, textvariable=set_minperiod)