Tidy up of Schools' Student Accounts Menu

In v 8.0.34 and above the 'Schools' Menu has been tidied up. 
Removed the following (any users requiring these options will now be using the Debtors & Invoices tables, so will see the NECOM menu instead):
- View payment summary
- Print payment list
​- Music lesson adjustments

Left the following options on the menu but greyed out (I think there may be one school that still uses these)
- View as List (Detail)
- Enter payments and print receipts 

Alos greyed out some buttons on the Billing Preview (schools) layout. They still work, but will be deleted from future versions unless anyone lets me know they still need them.