Initial commit.
Added code to read user's paper size symbol and get the integer part of it
if the size doesn't start with "A0...".
Cleaned up code that gets user input.
Added code to get paper size for A0 type entries.
Added code to find paper sizes.
This is based on two methods, depending on whether an Ax or A0 size was
entered by the user. The base case values of each method are hard coded.
I feel this shouldn't be the case, but it works and the hard coded values
are unlikely to change in the future.

One thing that may change/improve would be to combine these methods into one, and just
differentiate based on multiplying or dividing.