fluid~ prog message changed

hi, original code has prog messages indexed from 0, which I think is the correct way, see https://sourceforge.net/p/pure-data/svn/HEAD/tree/trunk/externals/footils/fluid/fluid/main.cpp#l193 Purr Data's version changed this, breaking backwards compatibility, by indexing it from 1, see https://git.purrdata.net/jwilkes/purr-data/-/blob/master/externals/fluid~/fluid~.c#L93

I see there's a new program method in smmf mode that also indexes from 1 and that also doesn't seem correct to me, but at least it's not breaking any backwards compatibility.

cheers