casa5

Merge pull request #522 in CASA/casa from feature/CAS-9538 to master

* commit 'bca18f9f8469559cf650d9727697884fad8c8515':
  A bug fix for interpolation setting
  Fixed the bug that if there is the existing CL file it won't overwrite it
  Added Perley-Butler 2013 and Perley-Butler 2017 as options for standard in predictcomp so that the task can be used for verification for this ticket
  help documenation update for Perley-Butler 2017 and addition of unit tests
  added Perley-Butler 2017 to the task interface
  minor update
  Modified the valid freq range handling and added a warning message
  2nd round of modifications to add Perley-Butler 2017
  initial modifications to add Perley-Butler 2017
  initial modifications for perley-butler 2017