Support for py.test

Change-Id: Id5ad1b6c99834653fca0846e72bf331dd2c8116d
Building tape type machinery -- common ttype_lookup routine
 - Working on ttype_lookup in cv_lib.py
 - Change cv prefix from 'cv' to 'cvv' so cv_lib does not match
 - Added test to detect duplicate functions
 - Eliminate duplicate functions (cv_popcart, cv_addcart,
   test_interpolation_{fail,ok}, test_addone, etc)

Change-Id: Icbebc6d6e72f0367726b18c708e314480822493d