Implement argument parsing for the assembler.

[donno]

This only requires the arguments be parsed and understood. They can print "not implemented" if they aren't implemented.

Options are as follows:

-l Generates a listing of your program and displays it to the terminal.
The listing shows how the assembler translated the program and
includes the symbol table.

-o The name of the object file or directory for saving objects
if multiple source files are provided.

The following two options are mutually elusive:
-a Generate absolute machine code.
-r Generate relocatable machine code.