USB virtual com port demo, works OK on SM1000

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1822 01035d8c-6547-0410-b346-abe4f91aad63
UT to measure rms noise on ADC ports

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1823 01035d8c-6547-0410-b346-abe4f91aad63