Replace EVAL and EXEC

In the old code, eval() and exec() were used to insert properties in
an object with an specific name. This is clearly an ugly solution,
when the right way is to use self.__setattr__ and self.__dict__.

This patch replaces that ugly code with new one that follows the
pythonic way of doing the things.

src/devedeng/file_movie.py

@@ -438,7 +438,7 @@ class file_movie(devedeng.interface_manager.interface_manager):
 
     def on_help_clicked(self, b):
 
-        help_file = devedeng.help.help("file.html")
+        devedeng.help.help("file.html")
 
     def properties(self):