Fix executable script name/path.

Index: wxGlade.desktop
--- wxGlade.desktop.orig
+++ wxGlade.desktop
@@ -3,7 +3,7 @@ Version=1.0.0
 Encoding=UTF-8
 Name=wxGlade
 Comment=A GUI designer written in Python with the popular GUI toolkit wxPython
-Exec=wxglade %f
+Exec=/usr/local/bin/wxglade %f
 Terminal=false
 Icon=wxglade.xpm
 Type=Application