2.0.0

• Parse - as an operand (generally used to tell a program to read from standard input) (#31).
• Add new opts.boolean (#30).
• Optimize the number of times options.unknown is invoked based on the fact that default and boolean options are known (#29).
• Optimize adding operands after -- (#25).
• Optimize aliases mapping by avoiding repeated array accesses (#24).
• Don't mutate options.default (#23).
• Optimize short flag splitting (#22).
• Access options.booleans map only once for every short option.