Formats a number adding commas.
    formatNumber(val, [groupSymbol], [decimalSymbol])
    
    
        | val | 
        string or number, a number to format | 
    
    
        | groupSymbol | 
        string, a group delimiter (default is comma) | 
    
    
        | decimalSymbol | 
        string, a group delimiter (default is dot) | 
    
    
 
The 
val argument can be an integer, float on in money format. The method will add commas (or
whatever 
groupSymbol you defined) after each there digits. This method will also format number
with a specified 
decimalSymbol.
Both 
groupSymbol and 
decimalSymbol are defined in 
w2utils.settings