This makes nicer the handling of layers in case of errors: only those allowed

Signed-off-by: emanuele <emanuele45@gmail.com>
 A small bit of documentation missing! Spuds will be shocked :P

Signed-off-by: emanuele <emanuele45@gmail.com>
Merge pull request #688 from emanuele45/fatal_errors

This makes nicer the handling of layers in case of errors