Fix template inheritance and other bugs in offline compression

Signed-off-by: Sigve Sebastian Farstad <sigvefarstad@gmail.com>
Update offline compression tests for multiple inheritance

Signed-off-by: Sigve Sebastian Farstad <sigvefarstad@gmail.com>
Add tests for offline compression with compress tag in base template

Signed-off-by: Sigve Sebastian Farstad <sigvefarstad@gmail.com>