Fix the class docs for the rst-syntax errors.

- Generate a correkt rst-syntax for the [/code] inline markup.
  (http://www.sphinx-doc.org/en/1.6.5/rest.html#inline-markup)
- Fix xml souce bugs

for the sphinx's rst syntax werrors:

class_area.rst:319: WARNING: Inline literal start-string without end-string.
class_area2d.rst:287: WARNING: Inline literal start-string without end-string.
class_audioserver.rst:287: WARNING: Inline literal start-string without end-string.
class_control.rst:509: WARNING: Inline literal start-string without end-string.
class_image.rst:422: WARNING: Inline literal start-string without end-string.
class_image.rst:434: WARNING: Inline literal start-string without end-string.
class_inputevent.rst:74: WARNING: Inline literal start-string without end-string.
class_inputeventaction.rst:45: WARNING: Inline literal start-string without end-string.
class_inputmap.rst:47: WARNING: Inline literal start-string without end-string.
class_kinematicbody.rst:80: WARNING: Inline interpreted text or phrase reference start-string without end-string.
class_kinematicbody2d.rst:80: WARNING: Inline interpreted text or phrase reference start-string without end-string.
class_line2d.rst:182: WARNING: Inline literal start-string without end-string.
class_thread.rst:51: WARNING: Inline literal start-string without end-string.
class_treeitem.rst:160: WARNING: Inline literal start-string without end-string.

doc/classes/Line2D.xml

@@ -63,7 +63,7 @@
 			<argument index="0" name="i" type="int">
 			</argument>
 			<description>
-				Returns point [code]i[code]'s position.
+				Returns point [code]i[/code]'s position.
 			</description>
 		</method>
 		<method name="get_points" qualifiers="const">