Replace string:tokens/2 with a custom command-line tokenizer that supports
single and double-quoted arguments (with embedded whitespace) and
expansion of environment variables using either the Unix ($VAR; ${VAR}) or
Windows (%VAR%) formats. This tokenizer is only used when the command line
is parsed as a single string.
This commit adds support for a type of command-line options that are
commonly used by many GNU tools. Now with this modification if you
have an option named 'verbose' with an integer argument and you enter
"-vvv" as in the command line you'll get {verbose, 3} as a result.