Belgian localization for in- and outgoing invoices (prereq to account_coda):
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- Rename 'reference' field labels to 'Communication'
- Add support for Belgian Structured Communication
A Structured Communication can be generated automatically on outgoing invoices according to the following algorithms:
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1) Random : +++RRR/RRRR/RRRDD+++
**R..R =** Random Digits, **DD =** Check Digits
2) Date : +++DOY/YEAR/SSSDD+++
**DOY =** Day of the Year, **SSS =** Sequence Number, **DD =** Check Digits
3) Customer Reference +++RRR/RRRR/SSSDDD+++
**R..R =** Customer Reference without non-numeric characters, **SSS =** Sequence Number, **DD =** Check Digits
The preferred type of Structured Communication and associated Algorithm can be
specified on the Partner records. A 'random' Structured Communication will
generated if no algorithm is specified on the Partner record.
