Countdown solver as a service in Go

• Basic page for / and /letters
• Unit tests
• Move dictionary into .go file to make binary completely portable
• Command-line flags
• Improve numbers round efficiency
• Generate numbers based on rules (new route too?)
• Benchmark tests using fuzzing
• Numbers round scoring
• Numbers round answer using fewest numbers?
• Improve efficiency of numbers
• Refactor perms and combi packages to use more consistent APIs
• Numbers round
• Error when no words are found
• Return JSON response
• JSON content-type header
• Better error handling
• Simple logging
• Upper limit on word length - long words can be very slow
• Time limit per search (not needed)~~
• Combi comments and example

• numbers/952,25,50,75,100,3,6 currently takes up to 384ms
• numbers/821,25,100,75,50,6,4
• numbers/556,50,8,3,7,2,10