This program decodes message files with two systems. The first one uses a a mapping system that mapps sequentially a letter from the alphabet to a letter in a cipher declared previously.
The second uses a Caesar Cipher, it's a technique in which each character in plain text is replaced by a character some fixed number of positions down to it. (For this program, it shifts 4)
-> Two header files to separate each method of decoding in which both inherits a pure virtual function from the base class
-> 1st Method: Mapping system
-> 2nd Method: Ceasar Cipher with 4 shifts