add parameter in sub definition of l_enc
remove sub createLaTeXTable, use createLaTexParams is more flexible
add some more parameters for invoice
fill in some more fields in the parameters
New functions for amount calculation:
- CalculateDiscount
- CalculateTax
- getAmount
These include discount and tax caclulation fully compatible with the
calculation that gnucash does.
use new sub getAmount to caculate all amounts. This includes now discount calculation
remove unused functions