Remove type conversion functionality from Options

Automatically converting the type is problematic, because if we change
the type of an option later (imagine str -> list), it'll pass the old
value to the new type constructor before any upgrade hooks are run.
With 6ff1f53, there shouldn't be any need to convert the types anyway
because sip now does that for us.

The 'convert' functionality has been repurposed here for actual format
conversions. As it happens, the only Option that needs that is the
password field (rot13).

picard/config.py

@@ -155,15 +155,16 @@ class Option(QtCore.QObject):
 
     registry = {}
 
-    def __init__(self, section, name, default, convert=None):
+    def __init__(self, section, name, default):
         self.section = section
         self.name = name
         self.default = default
-        self.convert = convert
-        if not self.convert:
-            self.convert = type(self.default)
         self.registry[(self.section, self.name)] = self
 
+    @staticmethod
+    def convert(value):
+        return value
+
     @classmethod
     def get(cls, section, name):
         try:
@@ -172,52 +173,20 @@ class Option(QtCore.QObject):
             raise KeyError("Option %s.%s not found." % (section, name))
 
 
-class TextOption(Option):
-
-    """Option with a text value."""
-
-    def __init__(self, section, name, default):
-        Option.__init__(self, section, name, default, unicode)
-
-
-class BoolOption(Option):
-
-    """Option with a boolean value."""
-
-    def __init__(self, section, name, default):
-        Option.__init__(self, section, name, default, bool)
-
-
-class IntOption(Option):
-
-    """Option with an integer value."""
-
-    def __init__(self, section, name, default):
-        Option.__init__(self, section, name, default, int)
-
-
-class FloatOption(Option):
-
-    """Option with a float value."""
-
-    def __init__(self, section, name, default):
-        Option.__init__(self, section, name, default, float)
-
-
 class PasswordOption(Option):
 
     """Super l33t h3ckery!"""
 
-    def __init__(self, section, name, default):
-        Option.__init__(self, section, name, default, rot13)
+    @staticmethod
+    def convert(value):
+        return rot13(value)
 
 
-class ListOption(Option):
-
-    """Option with a list of values."""
-
-    def __init__(self, section, name, default):
-        Option.__init__(self, section, name, default, list)
+TextOption = Option
+BoolOption = Option
+IntOption = Option
+FloatOption = Option
+ListOption = Option
 
 
 _config = Config()