add suffix option

closes #268

samples/saves/_save_filenames.rb

@@ -16,6 +16,10 @@ Squib::Deck.new(width: 50, height: 50, cards: 2) do
   # bar.png
   save_png prefix: ['foo', 'bar'], count_format: ''
 
+  # foo_00_bar.png
+  # foo_01_bar.png
+  save_png prefix: 'foo_', suffix: '_bar'
+
   # thief.png
   # thug.png
   data = csv data: "filename\nthief\nthug"

samples/saves/_saves.rb

@@ -45,6 +45,7 @@ Squib::Deck.new(width: 825, height: 1125, cards: 16) do
 
   # Sheets can arrange left-to-right and right-to-left
   save_sheet prefix: 'save_sheet_rtl_',
+             suffix: '_with_suffix',
              range: 0..1, rtl: true,
              columns: 2, rows: 1,
              margin: 75, gap: 5, trim: 37