Codec 2 optimised so that one less FFT is rqd, fdmdv C and Octave optimised so freq est ffts are only performed when reqd.  Codec 2 working OK, tfddmdv modem tests pass

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1806 01035d8c-6547-0410-b346-abe4f91aad63
changed cmake to Debug build so asserts() work again

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1807 01035d8c-6547-0410-b346-abe4f91aad63