v0.6.0

All arguments held by Argue are now stored as owned bytes (no more Cow). This will be a little slower than previous releases, but safer, as the state can now be maintained in the (unlikely) event the environment is later mutated.

The total number of keys are no longer restricted. Similarly, individual argument length restrictions have been removed. Go wild!

The different Unix implementations have all been merged together under the hood, so should now be more consistent across platforms. (This library is still not compatible with Windows.)

Other changes to note:

• Argue::peek, Argue::peek_unchecked have been removed (in favor of conventional indexing; see next two lines)
• Argue now implements std::ops::Index
• New: Argue::get, Argue::is_empty, Argue::len
• Argue::first_arg, Argue::first_arg_os have been removed (use Argue::arg(0) instead)