automated unit tests passing for new, memory efficient, downconvert and rx filter alg, fdmdv states now 40k, 10% of previous

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1718 01035d8c-6547-0410-b346-abe4f91aad63
UT to measure memory, and fixed to tfdmdv.c for new d/c + filter

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1719 01035d8c-6547-0410-b346-abe4f91aad63