*********** FINALLY OPENCART 3.0 READY ! ! ! ! ! *****************

VQMOD based - no Opencart core files changed.

This contribution allow a store owner/admin to assign a tax exemption to specific, single customers.
For this purpose, a new field "Exempted Tax Class" has been added in Admin->Sales->Customer->Edit form.

Possible values of this field/selectbox are:
- "None" (default)
- "All"
- tax class (all the tax classes defined in the store are shown in this select box)

If a specific tax class is selected, only products with that tax class will be exempted, otherwise all products or none.

Provided via vqmod in order to avoid any modification to core files (standard installation package available on request).