When sketch is saved as, old package name is kept

[codeanticode]

This happens when the original sketch has already been run, so the package name property in the manifest file is set, but does not get cleared when saving as.

[codeanticode]

Not clear if the package name should be reset when saving as, a typical situation is to have versions of the same sketch, say, sketch1 -> sketch2 ... etc. If the user already set a non-default package name, it is likely that in this situation may want to keep the package name since these sketches represent successive refinements of the same app.