zero argument macro parse bug

[StefanKarpinski]

julia> macro todo()
         :(error("TODO: unimplemented code called"))
       end

julia> @todo
TODO: unimplemented code called

julia> e = try     
         @todo
       catch e
syntax error: unexpected catch

Not sure of the general utility of zero-argument macros, but it seems like this ought to work.

[StefanKarpinski]

Actually, now that I think about it, zero-argument macros can be very handy for debugging. It's pretty common to pepper a section of code with the same debug statement that prints a bunch of state data, and which is often pretty long. Cut-and-paste makes this fairly easy, but just defining a macro and then writing @debug or just @d to print debug info is even easier and far less noisy. It also makes it easy to leave the @debug statements in and just make the macro emit a no-op to turn off all the debugging code.