Pull request #944: CAS-14487
Merge in CASA/casa6 from CAS-14487 to master
* commit '3b92c9c76c18ed828b613390b119223fd7359cec': CAS-14487: added test case 21 to the sdintimaging unit test, needs IRS1_7m_f.ms and JCMTsubre.image in the test data repo. CAS-14487: enabled sdint_helper to extract the Stokes I image from a full-Stokes SD image rather than just complaining about it CAS-14487: for usedata=='sdint', only permit stokes='I' CAS-14487: improved sdint_helper function copy_restoringbeam() by making better use of ia.setrestoringbeam() CAS-14487: cleaned up ia tool usage in calc_sd_residual() CAS-14487: in copy_restoringbeam, for single-plane image, remove restoringbeam completely before setting it again CAS-14487: merged the verified sdintimaging changes from CAS-14418 and further improved the handling of tool instances in sdint_helper.py CAS-14418: first iteration on a fix for making tmp file names unique. Added numerical 6-digit tag to the file names which is randomly created for each instance of the sdint_helper calls. The feather_residual() function needed to be moved from the task script to the sdint_helper class. Also the global instantiations of the sdint_helper and the synthesis utils classes were removed.
