Pad string arg1 to length arg2 using character arg3. arg3 is optional
and if omited will default to the ' '
(space) character. If arg2 is negative, the
string is padded on the left. If arg2 is
positive the string is padded on the right.
e.g.
STRPAD("fred", 10, "*")
will return the string "fred******"
STRPAD("fred", 10)
will return the string "fred "
STRPAD("fred", -10, "*")
will return the string "******fred"
STRPAD("fred", -10)
will return the string " fred"