fix test.
add better output to nit ignore (no args).
convert File instance to_s before serializing.
use #evaluate_index.
nit ignore now shows ignored files.
add StateTest.
change to #ignored_files=. make unignore work.
make nit unignore available.
make Files#[] accepts strings, too.
remove #evaluate_index as both ignores and files are now Files and come with #[] and #index.