Add a Key config type

Make sure any key we get from the config is normalized).

qutebrowser/config/configdata.yml

@@ -1811,8 +1811,8 @@ bindings.key_mappings:
     <Ctrl-[>: <Escape>
   type:
     name: Dict
-    keytype: String
-    valtype: String
+    keytype: Key
+    valtype: Key
   desc: >-
     This setting can be used to map keys to other keys.
 
@@ -2071,7 +2071,7 @@ bindings.commands:
                  'prompt', 'caret', 'register']
     valtype:
       name: Dict
-      keytype: String  # key
+      keytype: Key
       valtype: Command
   desc: >-
     Keybindings mapping keys to commands in different modes.

qutebrowser/config/configtypes.py

@@ -1016,7 +1016,7 @@ class Dict(BaseType):
         super().__init__(none_ok)
         # If the keytype is not a string, we'll get problems with showing it as
         # json in to_str() as json converts keys to strings.
-        assert isinstance(keytype, String), keytype
+        assert isinstance(keytype, (String, Key)), keytype
         self.keytype = keytype
         self.valtype = valtype
         self.fixed_keys = fixed_keys
@@ -1458,3 +1458,16 @@ class TimestampTemplate(BaseType):
                 value, "Invalid format string: {}".format(error))
 
         return value
+
+
+class Key(BaseType):
+
+    """A name of a key."""
+
+    def to_py(self, value):
+        self._basic_py_validation(value, str)
+        if not value:
+            return None
+        if utils.is_special_key(value):
+            value = '<{}>'.format(utils.normalize_keystr(value[1:-1]))
+        return value

qutebrowser/keyinput/basekeyparser.py

@@ -347,8 +347,7 @@ class BaseKeyParser(QObject):
     def _parse_key_command(self, modename, key, cmd):
         """Parse the keys and their command and store them in the object."""
         if utils.is_special_key(key):
-            keystr = utils.normalize_keystr(key[1:-1])
-            self.special_bindings[keystr] = cmd
+            self.special_bindings[key[1:-1]] = cmd
         elif self._supports_chains:
             self.bindings[key] = cmd
         elif self._warn_on_keychains:

tests/unit/config/test_configtypes.py

@@ -1801,6 +1801,20 @@ class TestTimestampTemplate:
             klass().to_py('%')
 
 
+class TestKey:
+
+    @pytest.fixture
+    def klass(self):
+        return configtypes.Key
+
+    @pytest.mark.parametrize('val, expected', [
+        ('gC', 'gC'),
+        ('<Control-x>', '<ctrl+x>')
+    ])
+    def test_to_py_valid(self, klass, val, expected):
+        assert klass().to_py(val) == expected
+
+
 @pytest.mark.parametrize('first, second, equal', [
     (re.compile('foo'), RegexEq('foo'), True),
     (RegexEq('bar'), re.compile('bar'), True),