Rewrote script to use more EL, introduced wrappers for sending pool:

Rewrote script to use more EL, introduced wrappers for sending pool:
- Introduced wrapper function getPaymentTime() and getPaymentPayment() and used
  both in EL code instead of PHP script
- Added new function library "pool-functions.php"
- Rewrote reading emails from "pool" table
- Rewrote updating of "pool data"
- TODOs.txt updated