Formats a number string.
Use: Result$=PVGadgets_FormatNumber(Number.s,Group.l,DecDig.l,DecSep.s,GrpSep.s,Neg.l)
Number.s - Number to format (in string format)
Group.l - group in bunches of
DecDig.l - number of decimal places
DecSep.s - Decimal separator character
GrpSep.s - Group seperator Character
Neg.l - Format negative values