Add option to specify output directory

Added option -o <directory> to specify output directory for all
files, currently including those in sub directories.
Add support for testing the archive(s) (instead of extracting)

* -t, --test will run the unarchivers test (for instance "unrar t
  archive.rar" instead of "unrar e archive.rar"
* Exit status is now the number of failed archives tested/extracted
* Color exit message green/red for OKs/fails
* Display the unarchivers error message on extract/test even when not
  running in verbose mode. Quiet mode will however suppress ALL messages.
* Add wrapper for 7z that sends (only) error messages to stderr
* Color error messages from cksfv red