This change brings this library's autoloading up to modern standards in
the larger PHP community and uses methods recommended by the PHP
dependency manager, composer.
From PSR-0 http://www.php-fig.org/psr/psr-0/
> As of 2014-10-21 PSR-0 has been marked as deprecated. PSR-4 is now
> recommended as an alternative.
PSR-4: http://www.php-fig.org/psr/psr-4/
From composer https://getcomposer.org/doc/04-schema.md#autoload
> PSR-4 is the recommended way since it offers greater ease of use (no
> need to regenerate the autoloader when you add classes).
While it is acceptable syntax, it is unnecessary and not recommended by
the PHP documentation:
https://secure.php.net/manual/en/language.namespaces.importing.php#language.namespaces.importing
> Note that for namespaced names (fully qualified namespace names
> containing namespace separator, such as Foo\Bar as opposed to global
> names that do not, such as FooBar), the leading backslash is
> unnecessary and not recommended, as import names must be fully
> qualified, and are not processed relative to the current namespace.
