Must include test harness before gtest

If gtest is include first then the operator<< for vector is not looked
up consistently.

Now only the SimpleITKTestHarness should include the gtest header.

Change-Id: I1be09066ad96da011b9d7299326b118a1b805dc7
Moving VectorDoubleRMS Predicate to cxx file

Change-Id: Ic351b7f7c6552c24d40b7f28ab55ea72989735cd
Adding inline keyword to functions in anonymous namespace

This is to address unused function warning emanating from clang 5.0.

Change-Id: I0b316d9be1ed700f1692e92cf7e6623f497c83a6
Merge topic 'SIMPLEITK-563_WrapCenteredVersorTransformInitializer' into next

962d464b Adding inline keyword to functions in anonymous namespace
9a4c14d4 Moving VectorDoubleRMS Predicate to cxx file
384e5ca4 Must include test harness before gtest