AMP for WP

Medium risk: 10 removed functions, 2 removed hooks, 1 removed asset handle.

• The filter ampforwp_age_gate_redirect_enabled is no longer fired. Any code hooked to it stops running silently.
• The filter ampforwp_age_gate_redirect_url is no longer fired. Any code hooked to it stops running silently.
• The function ampforwp_age_gate_add_return_arg() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_compat_template_redirect() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_enqueue_return_script() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_extract_return_from_url() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_filter_success_redirect() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_get_current_amp_url() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_get_return_amp_url() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_is_valid_amp_return_url() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_non_amp_url() was removed. Direct calls from a theme or another plugin will fatal.
• The function ampforwp_age_gate_return_to_amp_after_pass() was removed. Direct calls from a theme or another plugin will fatal.
• The script/style handle ampforwp-age-gate-return is gone. Code that dequeues, or declares a dependency on, that handle is now wrong.
• The constant AMPFORWP_AGE_GATE_RETURN_QUERY_VAR is no longer defined.
• The template templates/features.php changed. Any theme override of it is now out of date and will miss the change.