filter/msresamp2: unifying interp/decim methods

  * now includes 'type' field during initial creation (interp/decim)
  * consolidating separate methods
  * moving separate 'interp' and 'decim' methods to be internal only
  * much cleaner interface
filter/msresamp2: properly computing filter parameters
Merge branch 'msresamp2-dev'
filter/msresamp2: allowing object to be created with zero stages

  * effectively just pass data through without modification
  * tested with example program; seems to work fine
  * not necessarily useful, but simplifies future msresamp development
filter/msresamp: incorporating msresamp2 into object

  * using new multi-stage half-band resamapler internally
  * simplifies functionality
  * fixing issue with delay discrepancy
  * cleans up source code considerably