Decimal numbers for currency amounts

pokorra

We are now using the decimal type for all currency amounts, instead of double.

There are a few changes required:
On the gui, we should use txt, with Format=Currency. You will need to set the currency code in the ManualCode.
for example:

csharp\ICT\Petra\Client\lib\MFinance\gui\GL\UC_GLTransactions.yaml

txtDebitAmountBase: {Label=Dr Amount, ReadOnly=true, Format=Currency}

csharp\ICT\Petra\Client\lib\MFinance\gui\GL\UC_GLTransactions.ManualCode.cs

string BaseCurrency = FMainDS.ALedger[0].BaseCurrency;
txtDebitAmountBase.CurrencySymbol = BaseCurrency;

For exporting decimal values to file, the ToString() will print many zeros after the decimal points.
We should use ToString("0.##") to print just two digits after the decimal point.

TransactionAmount.ToString("0.##");