reduced no of avatars/run-tests in zombie defunct shell test
test refactoring
incoming and outgoing file hashes now stored, preparing the way for incremental tests (eg only saving a file it has changed - so it's filestamp remains unchanged)
output file handling tweak
added file_hash_diff function to diff incoming and outgoing file hashes
test tweak
added hidden_files method to language - working towards not deleting sandbox each run-tests
improved model/language tests