Added expression syntax documentation for fractional vector indices.
Added expression syntax documentation for fractional vector indices.

libmapper/libmapper,libmapper/libmapper,malloch/libmapper,libmapper/libmapper,libmapper/libmapper,malloch/libmapper,malloch/libmapper,malloch/libmapper,malloch/libmapper,malloch/libmapper,libmapper/libmapper,libmapper/libmapper