Explicitly closes warc log file after use.
Fixes ProgressRecorder print. Implements --ascii-print.

Fixes ProgressRecorder to print to stderr instead of stdout.

Implements --ascii-print to print message logs and progress in ASCII
with replacement characters.
hook.py: Fixes items not marked as done with FINISH action.
Explicitly use UTF-8 encoding for WARC log.
Uses backslashreplace for ASCIIStreamWriter errors.
Uses explicit UTF-8 encoding for output log.
hook.py: Fixes should_fetch not setting URLItem status.