New GL system

[TimSchofield]

Hi Paul, I have created a new branch called new_gl here (https://github.com/timschofield/webERP-svn/tree/new_gl) which you can pull to your own repository to work on.

I have added the new database items, updated DB_query() to generate new entries, and done the necessary changes to the CreatePeriod() function, and to the GLAccounts.php script as per the specification mentioned above. What needs doing now is to alter the reports, and check that the reports give the correct figures. That is the area where I don't haave the time to do all the work.

Tim