conf: Fix sorting of options with Python 3

__cmp__() is not supported anymore with Python 3 and cmp() is deprecated.
Instead rich comparisons should be used (only __lt__() is required for
sorting).

conf/format-options.py

@@ -67,8 +67,8 @@ class ConfigOption:
 		self.desc = []
 		self.options = []
 
-	def __cmp__(self, other):
+	def __lt__(self, other):
-		return  cmp(self.name, other.name)
+		return  self.name < other.name
 
 	def add_paragraph(self):
 		"""Adds a new paragraph to the description"""