BUILD: Enable RTTI again.
DEVTOOLS: Enable RTTI in create_project generated project files.
SDL: Let SdlGraphicsManager inherit from GraphicsManager.
SDL: Make activateManager/deactivateManager SdlGraphicsManager specific.

We can do this now that we can use virtual inheritance and dynamic_cast
because we enabled RTTI.
SDL: Further small cleanup related to manager switching.
BUILD: Enable RTTI on Android.

Thanks to fuzzie for these changes.
Merge pull request #409 from lordhoto/rtti

Enable RTTI and clean up the code by exploiting the availability of dynamic_cast.