Alpha-numeric Customer Numbers and some small bug fixes

Previously, Customer Numbers could only contain numerals - now they can be alpha-numeric. We have also added Customer Numbers to CSV exports.

We've encoded CSV downloads as UTF8 BOM so that excel opens them as UTF8 encoded so that it can read complex characters.

The Create New Product button within the Variations section of a Bottle's setup page was incorrectly creating the Variation as an "Other Product" instead of a Bottle. This has now been fixed.

On our EzyWine exports:

• We fixed small rounding errors due to transaction fee tax being excluded
• We fixed large rounding errors due to refunds not including the "R" suffix (both group by day which were being truncated and by order which wasn't including them)
• When a transaction type includes credit, we no longer render it as a SPLIT transaction unless its the only transactionType since credit is included as a line item anyway
• Ensure mix discounts on line items are included since mix totals are no longer stored on the mix itself