Start of streaming filter implementation.
Got streaming convolution working.
Added conv tests to RealFirFilterTest.
Restructured decimate.

Got RealFirFilter.decimateComplex working.  Need to do RealFirFilter.decimate.
Added a number of conv/decimation tests.
Changed how the decimate streaming works.
Added streaming interp function.

Still need complex version.
Added complex version of interp to RealFirFilter.
Converted resample method/function to virtual methods so we can do the filter streaming.
Added resample streaming to RealFirFilter.
Added a number of comments, and fixed some comments.