[PD] anti-aliasing table read (tabread4a~)

[Charles Henry]

Hi, list,
  I've finished programming and (preliminarily) testing an external,
which is based on tabread4~.  For normal speeds the operation is
identically tabread4~ , and for higher speeds, the interpolation
polynomial is modified to eliminate aliased frequencies.  The
transition is smooth and not noticable AFAICT. The compilation is
straightforward, you need math.h and m_pd.h.
The enclosed test patch will allow you to see/hear what it does.
March_of_the_sinusoids is a bit exaggerated, but will show you just
exactly what happens.

This is a preliminary release.  It has no major bugs that I know of,
but the error trapping on the bounds has not been implemented yet.  So
don't try accessing things outside of your table yet!!! (and as a
general rule, don't try it anyway)

plenty of room for improvement...I have some things in mind for it,
already, in terms of efficiency and for increasing the stop-band
attenuation, if the anti-aliasing is insufficient.

Chuck
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