Show (Call) Signature of object first.

When user press Shift+Tab to call up a Tooltip to show the information of a function/method/callable object, I suggest IPython display (Call) Signature fist, so that users can know to call the function quickly. For object with much information, the (Call) Signature will be hidden in Jupyter Notebook.

IPython/core/oinspect.py

@@ -658,6 +658,9 b' class Inspector(Colorable):'
 
         else:
             # General Python objects
+            append_field(_mime, 'Signature', 'definition', code_formatter)
+            append_field(_mime, 'Call signature', 'call_def', code_formatter)
+            
             append_field(_mime, 'Type', 'type_name')
 
             # Base class for old-style instances
@@ -671,9 +674,8 b' class Inspector(Colorable):'
                 append_field(_mime, 'Namespace', 'namespace')
 
             append_field(_mime, 'Length', 'length')
-            append_field(_mime, 'File', 'file'),
-            append_field(_mime, 'Signature', 'definition', code_formatter)
-
+            append_field(_mime, 'File', 'file')
+            
             # Source or docstring, depending on detail level and whether
             # source found.
             if detail_level > 0:
@@ -683,10 +685,8 b' class Inspector(Colorable):'
 
             append_field(_mime, 'Class docstring', 'class_docstring', formatter)
             append_field(_mime, 'Init docstring', 'init_docstring', formatter)
-            append_field(_mime, 'Call signature', 'call_def', code_formatter)
             append_field(_mime, 'Call docstring', 'call_docstring', formatter)
-
-
+            
 
         return self.format_mime(_mime)