new methods: safe_zone and cut_zone

spec/samples/samples_regression_spec.rb

@@ -51,6 +51,7 @@ describe 'Squib samples' do
       saves/_saves.rb
       saves/_showcase.rb
       shapes/_draw_shapes.rb
+      shapes/_proofs.rb
       text/_embed_text.rb
       text/_text_options.rb
       units/_units.rb
@@ -62,7 +63,7 @@ describe 'Squib samples' do
       Dir.chdir(File.dirname("#{samples_dir}/#{sample}")) do
         load full_sample_path
       end
-      overwrite_sample(sample, log) # Use TEMPORARILY once happy with the new sample log
+      # overwrite_sample(sample, log) # Use TEMPORARILY once happy with the new sample log
       test_file_str = File.open(sample_regression_file(sample), 'r:UTF-8').read
       expect(log.string).to eq(test_file_str)
     end