Large update of backend.

* Restructuring of database schema. Simplifying to one usertable and one profiletable.
* Offloading where suitable SQL-generation from php to stored procedures in the database.
  This reduces the nummber of connections to the server and simplifies php-code considerably.
* Added support for login with email.
* Created Triggers in MySQL for automatically storing publishing dates and update-dates for
  advertisements and profiles.
* Created Event in MySQL for handling automatic publishing and unpublishing of advertisements
  according to userspecified dates. Check will run each night at 00:00:00
* Update of datageneration-script according to the new database
* New API directory, for readme-files in html. Created one HTML-file for instructions to front-end how to connect and handle data.
* New database dump to import, now from sql/coderspool.sql