Improve usage reporting. Since imake is a principal application for tradcpp and imake carefully hides what it's doing when you run it, when rejecting an invalid option be sure to report *what* that option is.

#define a() x
a()
a ()
#define b(p) p
x/**/b(1)/**/x
x/**/b (1)/**/x
x/**/b()/**/x
#define c(p,q) p/**/q
x/**/c(1,2)/**/x
x/**/c(1)/**/x
x/**/c()/**/x