various tweaks and unit tests as SM1000 is brought up. ADC and DAC noise not too bad on loopbakc tests.  Currently bombs when freedv_api called

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1793 01035d8c-6547-0410-b346-abe4f91aad63
correct varicode init

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1794 01035d8c-6547-0410-b346-abe4f91aad63