Fixed ANSI compliance issue in AnsiCodeProcessor.

Among other things, this fixes 'ls' on Mac OS. I also added a safety SGR reset in FrontendWidget to prevent bad ANSI codes from hosing the input buffer.

IPython/frontend/qt/console/ansi_code_processor.py

@@ -104,8 +104,11 b' class AnsiCodeProcessor(object):'
             The parameter codes for the command.
         """
         if command == 'm':   # SGR - Select Graphic Rendition
-            for code in params:
-                self.set_sgr_code(code)
+            if params:
+                for code in params:
+                    self.set_sgr_code(code)
+            else:
+                self.set_sgr_code(0)
 
         elif (command == 'J' or # ED - Erase Data
               command == 'K'):  # EL - Erase in Line

IPython/frontend/qt/console/frontend_widget.py

@@ -265,6 +265,12 b' class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):'
             # before writing a new prompt.
             self.kernel_manager.sub_channel.flush()
 
+            # Reset the ANSI style information to prevent bad text in stdout
+            # from messing up our colors. We're not a true terminal so we're
+            # allowed to do this.
+            if self.ansi_codes:
+                self._ansi_processor.reset_sgr()
+
             content = msg['content']
             status = content['status']
             if status == 'ok':