Removal of Symbian support

Qt Creator's support for Symbian was at its peak in version
2.4.x. Nobody really verified it in Qt Creator 2.5 or 2.6.
It is most likely rotten. Let's remove it!

Also, the Symbian support code was spread throughout the whole
Qt Creator code base. The plugin interfaces evolved in the
meantime and target platforms like Android or QNX have 99% of
their code in separate plugins.

In case anyone wants to revive Symbian support in Qt Creator,
please create a plugin for it.

Change-Id: I56a758a3e2fd5b8c64d9aeb8f63d8e916c4883be
Reviewed-by: Alessandro Portale <alessandro.portale@nokia.com>

doc/src/projects/creator-projects-creating.qdoc

@@ -68,15 +68,6 @@
     use \QC as a code editor and to fully control the steps and commands used to
     build the project.
 
-    \if defined(qcmanual)
-    To develop applications for Symbian devices, you use qmake and the local
-    Symbian compiler (on Windows) or qmake and a compilation service at
-    Nokia Developer (on Linux and Mac OS) to build the applications for the
-    Symbian devices target. The interface to the compilation service,
-    Remote Compiler, is installed as a part of the \QSDK. For more information,
-    see \l{Building with Remote Compiler}.
-    \endif
-
     You can install mobile device \l{glossary-development-target}{targets}
     as part of the \QSDK. The build and  run settings for the
     installed targets are set up automatically. However, you might need to
@@ -129,13 +120,6 @@
                 interfaces with a custom look and feel and QML and C++ code to
                 implement the application logic
 
-            \o  Qt Quick Application for Symbian
-
-                Use Qt Quick Components for Symbian to design a user interface
-                with the platform look and feel. Select this template to develop
-                for Symbian devices that support Qt 4.7.4 or later and have the
-                Qt Quick Components installed
-
             \o  Qt Quick Application for MeeGo Harmattan
 
                 Use Qt Quick Components for MeeGo Harmattan to design a user