[Draft] Add dumping functions

[DanielPointon]

Here's as far as I got:

• Reverse engineered the file parsing code to make two functions, MultiplicationFileToString and MultiplicationFilesToString.
• Tested that they work for n=3, as follows

gap> GenerateMultiplicationTableArray := function(n)                                                                                                
>     local results, i;                                                                                                                             
>     results := [];                                                                                                                                
>     for i in [1..18] do                                                                                                                           
>         Add(results, RecoverMultiplicationTableNC(n, i));                                                                                         
>     od;                                                                                                                                           
>     return results;                                                                                                                               
> end;;                                                                                                                                             
gap>                                                                                                                                                
gap> MultiplicationTablesToString(GenerateMultiplicationTableArray(3));                                                                             
"001000000110000001\n021000002020000002\n001000000110000011\n000000000001111112\n020000012120011210\n021000202020200222\n020001212120212220\n00012\ 
2222222222221"                        

Which is the correct file contents for n=3

• Added some basic infrastructure that I think would work for loading these new files in.

Hopefully that helps the next person (most likely me) who looks at gap-packages#31