DirSearch is a class that reads the filelist, find a match between the expression and a word in the filelist, and store all the files that contain that word
Goofi class search through a website or directory, store all the files within the directory or website into a file call filelist and store all the unique words in all files into a file call wordlist
a quitting class, used when windows are closed or
quit menu item chosen (or any other quit action event)
pattern: uses singleton for one instance per program
inheritance: subclasses can override doQuit() for application-specific
cleanup