ENH: Improve ResampleImage isotropic spacing precision.

Use compensated summation for calculating the output spacing.

Treat space location inputs to ResampleImage as double.

Update the required baseline.

Change-Id: If7828a260fced4e65e6431562c021e966455e946
ENH: Add --toleranceCoordinates flag to ImageCompareCommand.

This flag allows a different tolerance in coordinates on image origin and
spacing.

Change-Id: I24759d25d91f50c70fea25b926b598d3662597cc
BUG: Increase spacing tolerance for ResampleImage-Test2-Compare.

Fixes test on Windows.

Change-Id: I3f52a3a7961e248177f72f8a80c612b9a800a00a
BUG: Add another baseline for ResampleImageTest1.

For Windows.

Change-Id: Id530e668efb1e9242e252555e96a48e91c5f2d7e
ENH: Better feedback in .pth testing site-packages installation.
BUG: Do not try to use virtualenv testing environment with Slicer.

The Slicer Python is not compatible with virtualenv.
Merge pull request #210 from thewtex/slicer-python

Slicer python
Merge pull request #209 from thewtex/resample-precision

Resample precision