reenable multiline history for terminals

Add configuration variable InteractiveShell.multiline_history.
If it is True cells spanning multiple lines will be saved in history
as a single entry instead of one entry per line, as was the case in
ipython < 0.11.
closes gh-571

IPython/core/interactiveshell.py

@@ -307,6 +307,9 b' class InteractiveShell(SingletonConfigurable, Magic):'
         Automatically call the pdb debugger after every exception.
         """
     )
+    multiline_history = CBool(False, config=True,
+        help="Store multiple line spanning cells as a single entry in history."
+    )
 
     prompt_in1 = Unicode('In [\\#]: ', config=True)
     prompt_in2 = Unicode('   .\\D.: ', config=True)
@@ -1721,6 +1724,10 b' class InteractiveShell(SingletonConfigurable, Magic):'
         for _, _, cell in self.history_manager.get_tail(1000,
                                                         include_latest=True):
             if cell.strip(): # Ignore blank lines
+                if self.multiline_history:
+                      self.readline.add_history(py3compat.unicode_to_str(cell.rstrip(),
+                                                                         stdin_encoding))
+                else:
                 for line in cell.splitlines():
                     self.readline.add_history(py3compat.unicode_to_str(line,
                                                                 stdin_encoding))

IPython/frontend/terminal/interactiveshell.py

@@ -229,6 +229,15 b' class TerminalInteractiveShell(InteractiveShell):'
                     # handling seems rather unpredictable...
                     self.write("\nKeyboardInterrupt in interact()\n")
 
+    def _store_multiline_history(self, source_raw):
+        """Store multiple lines as a single entry in history"""
+        if self.multiline_history and self.has_readline:
+            hlen = self.readline.get_current_history_length()
+            lines = len(source_raw.splitlines())
+            for i in range(1, min(hlen, lines) + 1):
+                self.readline.remove_history_item(hlen - i)
+            self.readline.add_history(source_raw.rstrip())
+
     def interact(self, display_banner=None):
         """Closely emulate the interactive Python console."""
 
@@ -281,7 +290,7 b' class TerminalInteractiveShell(InteractiveShell):'
                 #double-guard against keyboardinterrupts during kbdint handling
                 try:
                     self.write('\nKeyboardInterrupt\n')
-                    self.input_splitter.reset()
+                    self._store_multiline_history(self.input_splitter.source_raw_reset()[1])
                     more = False
                 except KeyboardInterrupt:
                     pass
@@ -309,6 +318,7 b' class TerminalInteractiveShell(InteractiveShell):'
                     self.edit_syntax_error()
                 if not more:
                     source_raw = self.input_splitter.source_raw_reset()[1]
+                    self._store_multiline_history(source_raw)
                     self.run_cell(source_raw, store_history=True)
 
         # We are off again...