Blender Git Loki

Defaults: refactor startup.blend code, more consistely apply to templates

There were various changes only applied to specific builtin templates even
though they should apply to all, since it's possible to do e.g. use grease
pencil objects in the general template or use mesh sculpting in the grease
pencil template.

Also, nearly all changes now apply to builtin templates only. This was
already the case for most, and the distinction seems to have been more by
accident than intent.