[PD] Abstraction arguments: tell apart symbols from floats from no argument at all

[Peter P.]

* Christof Ressi <christof.ressi at gmx.at> [2018-12-22 17:15]:
> if you're ok with externals you can also use [dollarg] from iemlib or [canvasargs] from iemguts. for a hacky vanilla solution, see attached patch. I'm sure there are more ways, this is just one that I remembered.
And it is a nice one, Thanks Christof!
P