example crashes o n windows (vs22) in debug builds

[dbadb]

dspOpsExample.cpp crashes on windows (vs22) in debug builds because of its built-in boundary checking.

The issue seems to be related to default constructed delay lines that never get setMaxDelay called. This occurs, for example, in the FDN<4> instantiation. I believe the same is true for FeedbackDelayFunction.

While we're at it

• this line doesn't compile since mCoeffs isn't a member, but _coeffs is

lp1.mCoeffs = Lopass::coeffs(0.25, 1.0);

• more obscurely, the example doesn't compile with the win32 + clang compiler. I haven't dug into the details for that.