Made Project() constructor global so that it can be actually used by files dofile'ing project.lua.
Fixed variable name typo.
Made source_files a private member variable of Project. Added functions to add source files to a Project, and print the currently stored source files.
Added tables for include paths, link paths, and libraries to Project tables, with functions to add to each of them.
Renamed sources to source_files.
Replaced unused variable 'k' with underscore.
Added Project variable for output name.