Modifications to compile Centurion Assembler from AgentOrange with GNU c++

[jpelletier]

In instruction.cpp,

• change all 'AX' to "AX"
• at line 649, change == for +=
• at line 640, change sourceLine to std::to_string(sourceLine)

In instruction.h,

• add #include <string>
• at line 11, in the constructor, add the default value: int lineNum = 0

In point.h,

• add #include <string>

In README.MD,

• change teh for the

The code compile and links but executing the program without a parameter segfaults.