Draft: Fixes in trackers

* Plane tracker can now be turned off in preferences
* Grid no longer stays in front of new objects

src/Mod/Draft/Draft.py

@@ -108,7 +108,7 @@ def getParamType(param):
         return "float"
     elif param in ["selectBaseObjects","alwaysSnap","grid","fillmode","saveonexit","maxSnap",
                    "SvgLinesBlack","dxfStdSize","showSnapBar","hideSnapBar","alwaysShowGrid",
-                   "renderPolylineWidth"]:
+                   "renderPolylineWidth","showPlaneTracker"]:
         return "bool"
     elif param in ["color","constructioncolor","snapcolor"]:
         return "unsigned"