v0.5.1

• Add support for tasks depending on directories
• New fast_dirs mode in TaskManager for cheaper directory checks
• Add progress callback
• Add support for passing blocks to Tasks:

Croupier::Task.new output: "fileA", inputs: ["input.txt"] do
  puts "task1 running"
  File.read("input.txt").downcase
end

Full Changelog: v0.5.0...v0.5.1