New IncrediBuild plugin

- Using raw pointers instead of QSharedPointers.
- Removing redundant pointers existence checks before delete.
- Replacing empty quotes with explicit QString() instance creation.
- A few spaces and tab fixes.
- Save settings after migrating build steps

Change-Id: Iff87d75c7047474ab8e49366ddfeced766ff1a67
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/plugins.qbs

@@ -44,6 +44,7 @@ Project {
         "helloworld/helloworld.qbs",
         "help/help.qbs",
         "imageviewer/imageviewer.qbs",
+        "incredibuild/incredibuild.qbs",
         "ios/ios.qbs",
         "languageclient/languageclient.qbs",
         "macros/macros.qbs",