Modify Expiration Reminder Add Expiration Reminder

##f_t## 

##f_v## ##f_txt##
Placeholders available in mail message:
##hw_days_rem## - days before {item} expiry
##email## - user email
##link_id## - {item} id
##ad_url## - {item} url
##cname## - category name
##email_rows## - {item} fields
##hw_days_rem## - days before user account expiry
##email## - user email
##username## - username
##hw_days_rem## - days before {item} extra option expiry
##extra_opt_descr## - extra option description
##extra_opt_val## - extra option value
##email## - user email
##link_id## - {item} id
##ad_url## - {item} url
##cname## - category name
##email_rows## - {item} fields