Subcommands for working with multi-dimensional values #42

E.g.

wp_update_option('example_option', array('foo' => 'bar'));

wp option pluck example_option foo
# or 
wp option get example_option --key=foo

Returns bar

wp option patch example_option foo baz
# or
wp option set example_option --key=foo baz

Updates bar to baz

Ideally it would be great to be able to use dot notation using the normal functions, but option names could contain dots or really any other character that could be used to separate hierarchy.

e.g.

wp option get example_option.foo

Returns bar

This same idea could be applied to just about all get set commands, for meta, transient, etc.