Renamed -n flag to -t and added -v and -o

"name" has been changed to "title" for consistency, but is still used in
the same way:

  -t TITLE, --title TITLE
                        give the graph a custom title

-v and -o flags have not yet been implemented but will be used as
follows:

  -v, --verbose         print verbose messages

  -o NAME, --output NAME
                        specify output filename. Do not include extension

The reason for not specifying the extension with the -o flag is because
multiple extensions can be specified with the -f flag.
Implemented output location selection

Usage:
  -o NAME, --output NAME
                        specify output filename. Do not include extension

The extension should be chosen separately using the -f flag
Updated README to reflect -o flag addition