Update IPython/core/formatters.py to use new traitlets API.

Also remove an unused import.

IPython/core/formatters.py

@@ -11,7 +11,6 b' Inheritance diagram:'
 # Distributed under the terms of the Modified BSD License.
 
 import abc
-import inspect
 import json
 import sys
 import traceback
@@ -36,7 +35,7 b' from IPython.utils.py3compat import ('
 class DisplayFormatter(Configurable):
 
     # When set to true only the default plain text formatter will be used.
-    plain_text_only = Bool(False, config=True)
+    plain_text_only = Bool(False).tag(config=True)
     def _plain_text_only_changed(self, name, old, new):
         warnings.warn("""DisplayFormatter.plain_text_only is deprecated.
         
@@ -50,7 +49,7 b' class DisplayFormatter(Configurable):'
         else:
             self.active_types = self.format_types
     
-    active_types = List(Unicode(), config=True,
+    active_types = List(Unicode()).tag(config=True,
         help="""List of currently active mime-types to display.
         You can use this to set a white-list for formats to display.
         
@@ -288,21 +287,21 b' class BaseFormatter(Configurable):'
     format_type = Unicode('text/plain')
     _return_type = string_types
 
-    enabled = Bool(True, config=True)
+    enabled = Bool(True).tag(config=True)
 
     print_method = ObjectName('__repr__')
 
     # The singleton printers.
     # Maps the IDs of the builtin singleton objects to the format functions.
-    singleton_printers = Dict(config=True)
+    singleton_printers = Dict().tag(config=True)
 
     # The type-specific printers.
     # Map type objects to the format functions.
-    type_printers = Dict(config=True)
+    type_printers = Dict().tag(config=True)
 
     # The deferred-import type-specific printers.
     # Map (modulename, classname) pairs to the format functions.
-    deferred_printers = Dict(config=True)
+    deferred_printers = Dict().tag(config=True)
     
     @catch_format_error
     def __call__(self, obj):
@@ -569,9 +568,9 b' class PlainTextFormatter(BaseFormatter):'
 
     # This subclass ignores this attribute as it always need to return
     # something.
-    enabled = Bool(True, config=False)
+    enabled = Bool(True).tag(config=False)
     
-    max_seq_length = Integer(pretty.MAX_SEQ_LENGTH, config=True,
+    max_seq_length = Integer(pretty.MAX_SEQ_LENGTH).tag(config=True,
         help="""Truncate large collections (lists, dicts, tuples, sets) to this size.
         
         Set to 0 to disable truncation.
@@ -582,21 +581,21 b' class PlainTextFormatter(BaseFormatter):'
     print_method = ObjectName('_repr_pretty_')
 
     # Whether to pretty-print or not.
-    pprint = Bool(True, config=True)
+    pprint = Bool(True).tag(config=True)
 
     # Whether to be verbose or not.
-    verbose = Bool(False, config=True)
+    verbose = Bool(False).tag(config=True)
 
     # The maximum width.
-    max_width = Integer(79, config=True)
+    max_width = Integer(79).tag(config=True)
 
     # The newline character.
-    newline = Unicode('\n', config=True)
+    newline = Unicode('\n').tag(config=True)
 
     # format-string for pprinting floats
     float_format = Unicode('%r')
     # setter for float precision, either int or direct format-string
-    float_precision = CUnicode('', config=True)
+    float_precision = CUnicode('').tag(config=True)
 
     def _float_precision_changed(self, name, old, new):
         """float_precision changed, set float_format accordingly.