more tests and a few tips
improved the introduction to the exercises
simplified eeeeverything in GroceryShopping
tests for parseIngredient
removed unused type alias
more hints for parseIngredient
Initial version of slides for lesson C
Adding Vigenere-exercise and tests for it
Adding credit card number validator exercise
Adding credit card number-validation tests
Renaming function for mod 10
Removing unused code and adding spacing
A bit more description of the Vigenere encryption
Merge pull request #4 from tobiasgwaaler/lessonc-tobias

Lesson C, Tobias
Merge branch 'master' into vigenere
Added CreditCardNumberValidatorTests to main test file
Added Vigenere-tests to main test function
Merge pull request #5 from tobiasgwaaler/vigenere

Vigenere
aligned with solutions branch
Merge branch 'lessonc-tobias'