* Minor fix for the problem that Net Total, Net Rate, Net Amount field would not be shown when default taxes were fetched
* Prevent net_rate from becoming NaN
* -Fixed problem that party_account_currency was not set in mapped document
-Fixed problem that discount amount was not recalculated (in mapped document)
-Fixed problem that set_dynamic_fields would work only on certain condition that led to showing Total (Company Currency) field even when using company currency