Parametric factor function APIs for indirect use from MATLAB

 - Pruned IFactorFunction interface and attached to FactorFunction
 - Created IParametricFactorFunction interface with methods for accessing
   parameters by name
 - Implemented parametric interface in a number of factor functions
 - Added tests
Merge branch 'master' of seymour.lyricsemiconductor.com:LyricLabsADI/dimple
Disable TestJSFactorFunction test - doesn't work on linux