QR Code tag: lot of warnings/errors on plugin activation

I got bunch of errors and warnings after activating this plugin and even after.
Here is the output:

Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; QrctWp has a deprecated constructor in /testsite.com/wp-content/plugins/qr-code-tag/lib/qrct/QrctWp.php on line 11

Notice: wp_enqueue_script was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.0.) in /testsite.com/wp-includes/functions.php on line 4146

Notice: wp_enqueue_script was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.0.) in /testsite.com/wp-includes/functions.php on line 4146

Notice: wp_enqueue_script was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.0.) in /testsite.com/wp-includes/functions.php on line 4146

Notice: wp_enqueue_style was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.0.) in /testsite.com/wp-includes/functions.php on line 4146

Notice: register_widget_control is deprecated since version 2.8.0! Use wp_register_widget_control() instead. in /testsite.com/wp-includes/functions.php on line 3838

Notice: has_cap was called with an argument that is deprecated since version 2.0.0! Usage of user levels is deprecated. Use capabilities instead. in /testsite.com/wp-includes/functions.php on line 4030

Warning: Cannot modify header information - headers already sent by (output started at /testsite.com/wp-content/plugins/qr-code-tag/lib/qrct/QrctWp.php:11) in /testsite.com/wp-admin/includes/misc.php on line 1114

Plugin’s author, please update this wonderful thing!