Bump WP compatibility

See merge request !7

Bump WP compatibility

See merge request !6

Bump WP compatibility

See merge request !5

Remove rsync dependency

See merge request !4

Automated WP.org updates

See merge request !3

Introduce WP-CLI plugin scaffold bits

See merge request !2

PHP 7.3 compatibility

See merge request !1

Per https://make.wordpress.org/core/2015/07/02/deprecating-php4-style-constructors-in-wordpress-4-3/, WP 4.3 deprecates PHP4-style widget constructors, and their usage will trigger deprecated notices. Switching to PHP5 constructors is simple and resolves the problem.

* Support for WordPress 4.2 and its splitting of shared terms
* Correct line endings in readme file

Fixes #1.

WP has set the expectation that arguments can be specified as strings joined by ampersands. While I think it's an unnecessarily-confusing way of specifying arguments, some users seem to like it.

See http://wordpress.org/support/topic/unable-to-customise-plugin-behaviour-in-non-widget-implementation.

Introduced in e696a372.