Fixing loss of point-precision in certain filters.

Certain filters tend to loose point precision and end up converting double point
arrays to flot arrays. This patch address the issue for a few filters using the
API added to vtkAlgorithm by commit 49d1f124.

Change-Id: I8740e4e4bfdd9944fbadb45744038e42eff04830
Fix testing macros.

add_test_python() and add_test_python1() had incorrect logic due to which even
when the macros were called with no baseline directory specified, they would
still add arguments to check baselines. That was causing some new tests (viz.
pointsPrecisions) to fail since they didn't expect those command line arguments.
This address that issue.

Change-Id: Idd558afc8bdacb25ff928460efb482716097d347
Merge topic 'fix_filter_precisions' into master

8803e22c Fix testing macros.
f830ef4c Fixing loss of point-precision in certain filters.