Merge pull request #188 in CASA/casa6 from CAS-10891 to master
* commit 'c11f2f89f82075b81a0372f39a36a315c523b0ef':
update test codes based on Renaud's comments
update tsdimaging unit tests to not use os.system()
update unit test code for tsdimaging based on comments from Renaud and Sumi.
update tsdimaging codes based on comments from Takeshi
modify tsdimaging to not output sumwt. unit test is updated also.