Factored out the main() function and created a secondary/intermediate Makefile.

In an attempt to make the functions more modular, I factored out the
main function into its own file and made a header file for builder.c
which is then referenced by main.c. This allows make to then compile it
all together.

The code will now compile when running "make" from within the "src"
directory.

TODO: integrate connect.c and integrate.c to the Makefile.