Added touch input example

Author: kattni

examples/slideshow_touch.py

@@ -0,0 +1,26 @@
+from adafruit_slideshow import PlayBackMode, SlideShow, PlayBackDirection
+import touchio
+import board
+
+forward_button = touchio.TouchIn(board.TOUCH4)
+back_button = touchio.TouchIn(board.TOUCH1)
+
+brightness_up = touchio.TouchIn(board.TOUCH3)
+brightness_down = touchio.TouchIn(board.TOUCH2)
+
+slideshow = SlideShow()
+slideshow.order = PlayBackMode.ALPHA
+slideshow.auto_advance = False
+slideshow.dwell = 0
+
+while True:
+    if forward_button.value:
+        slideshow.advance()
+    if back_button.value:
+        slideshow.advance(direction=PlayBackDirection.BACKWARD)
+
+    if brightness_up.value:
+        slideshow.backlight_level_up()
+    elif brightness_down.value:
+        slideshow.backlight_level_down()
+    slideshow.update()