fix typo

src/Theme.py

@@ -155,7 +155,7 @@ def get(value, type = str, default = None):
     #since the original Frets on Fire.  What glow_color allows you to do is set it so
     #the glow is either the color of the fret it's over or it can be the color the image
     #actually is (if the image is white then no matter what key is hit the glow will be white)
-    self.glowColor   = get("glow_color",       str,    "fret")
+    self.glowColor   = get("glow_color",       str,    "frets")
     if not self.glowColor == "frets":
         self.glowColor = self.hexToColor(self.glowColor)