Use the internal buffer of a spread directly to avoid memory allocations on large object heap when dealing with high spread counts.

This basically solves issue described here: http://vvvv.org/forum/cyclic-framerate-drops
Note: This commit depends on a0c052dc9558c01e9cebcd5689baac614493305a in git@github.com:azeno/FeralTic.git - I don't know how to do a commit properly which affects a forked submodule.