introduce Gemgem.init to populate lib and dir
also prepend bin to PATH
never use relative path, so we are not depending on cwd
introduce test_files
introduce bin_files
only check for markdown files now
--git-dir
now we have test_files
let's remove all cwd assumption
pathname is so slow if cwd is outside of the project. remove it!
now it's much faster, simpler, and easier to understand!

missing feature: negative pattern in .gitignore