Doc: replace deprecated QDoc commands

The \i and \o commands were replaced with \li and
\bold was replaced with \b in QDoc for Qt 5.

The \input command was replaced with \include in the docs.

Change-Id: I257d1bebb8ebc739ca20e0d29fcf0406ecb14534
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>

src/libs/extensionsystem/pluginmanager.cpp

@@ -80,8 +80,8 @@ enum { debugLeaks = 0 };
 
     The plugin manager is used for the following tasks:
     \list
-    \o Manage plugins and their state
-    \o Manipulate a 'common object pool'
+    \li Manage plugins and their state
+    \li Manipulate a 'common object pool'
     \endlist
 
     \section1 Plugins
@@ -186,13 +186,13 @@ enum { debugLeaks = 0 };
         };
     \endcode
 
-    \bold Note: The type of the parameters passed to the \c{invoke()} calls
+    \note The type of the parameters passed to the \c{invoke()} calls
     is deduced from the parameters themselves and must match the type of
     the arguments of the called functions \e{exactly}. No conversion or even
     integer promotions are applicable, so to invoke a function with a \c{long}
     parameter explicitly use \c{long(43)} or such.
 
-    \bold Note: The object pool manipulating functions are thread-safe.
+    \note The object pool manipulating functions are thread-safe.
 */
 
 /*!