set default names of silk layers Currently, the names of the two silk layers are set to the exact same value. This patch set their name to "top silk" and "bottom silk".

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Show the actual name of silk layers in the GUI

This patch makes the GTK GUI show the actual name of the silk layer, rather
than a hard coded "silk". The layer name in silk gets updated if the view is
swapped.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>