Pull request #1063: CAS-14797
Merge in CASA/casa6 from CAS-14797 to master
* commit 'd0332c4e3cda643f0a1b8a128c35f1a6ee2e973f':
Streamline the implementations of helper functions in just two helper functions now made available in MatrixCleaner.cc
Search only over inner square
Make MSMT-CLEAN compatible with previous runs again
repeat same accelerations for AspMatrixCleaner and for MultiTermMatrixCleaner
This code will increase the speed for MS-CLEAN. This is achieved by two main improvements: -> Subtract beam is faster than casacore functionality which creates temporary copies -> Run peak finding only over square determined by blcdirty and trcdirty rather than the full image -> again, the direct implementation is faster than casacore minMax functionality
