Add LIMIT to the Recurring Email Reminder functionality.

[andrewlimaza]

We should add in a SQL LIMIT clause that is filterable for the recurring email reminder logic (Around here -

paid-memberships-pro/scheduled/crons.php

Lines 278 to 297 in 7c9031c

	$sqlQuery = $wpdb->prepare(
	"SELECT subscription.*
	FROM {$wpdb->pmpro_subscriptions} subscription
	LEFT JOIN {$wpdb->pmpro_subscriptionmeta} last_next_payment_date
	ON subscription.id = last_next_payment_date.pmpro_subscription_id
	AND last_next_payment_date.meta_key = 'pmprorm_last_next_payment_date'
	LEFT JOIN {$wpdb->pmpro_subscriptionmeta} last_days
	ON subscription.id = last_days.pmpro_subscription_id
	AND last_days.meta_key = 'pmprorm_last_days'
	WHERE subscription.status = 'active'
	AND subscription.next_payment_date >= %s
	AND subscription.next_payment_date < %s
	AND ( last_next_payment_date.meta_value IS NULL
	OR last_next_payment_date.meta_value != subscription.next_payment_date
	OR last_days.meta_value > %d
	)",
	date_i18n( 'Y-m-d', strtotime( "+{$previous_days} days", current_time( 'timestamp' ) ) ),
	date_i18n( 'Y-m-d', strtotime( "+{$days} days", current_time( 'timestamp' ) ) ),
	$days
	);

).

This will allow developers more control over the number of emails to process per cron job.