Code init
Added a help function

This is a default, catch all function that, in future, will print how
the application is used.
Added a menu function

This function will provide choices using flags. Still needs some work.
Added a check validity of date

This function checks if the date entered is valid using this
parameters: the default format, and the length of a month and a year.
It prints a helpful message if the format and/or validity is wrong.
Added a date separator

To make calculating easier the date is separated to day, month, year
integer array.
Added a distance function

Added some basic work that needs to be done before we even start the
calculations.
Added an adder function

Just a place holder.
Code that calls the menu function.

We take a first argument and send it to a menu function. I have to add
a validity checker here (catch all) to menu function.
I can't user git.