Added multi threaded^H^H^H^H^H^H^H core version
Corrections to parallel FIR and documentation
First attempt at feedback noise cancellation
Merge branch 'master' of ssh://github.com:22/xcore/sc_dsp_filters

* 'master' of ssh://github.com:22/xcore/sc_dsp_filters:
  More fixes for 12.2 build
  More fixes to get things to build with 12.2 tools
  Ensuring top-level make works with 12.2 tools
Attempt at repairing new makefile