Letter and Large Letter rates have now become 'First Class Letter' and 'First Class Large Letter', and I have created two new rates for Second Class Letter and Second Class Large Letter. This was the best way to fix the issue where second class letter/large letter didn't exist and to ensure functionality won't break when a user upgrades the extension.
Bug fix for international economy, this should be a negative check as it was previously: https://github.com/meanbee/royalmail/pull/13/files#diff-8125a79c8c56d79d9ebe841ccca8a885L24. Further to this, both first class and first class recorded signed for tests has incorrect pricing.
PHPUnit tests created for Second Class Large Letter and Second Class Letter
Updated copyright year/company name
replaced country code with constant
Merge pull request #19 from ashsmith/second-class-letter-fix

Second class letter fix