Fix for `PATH` separator in `BaseNodeFilter`

Make it platform agnostic with `PATH_SEPARATOR`.
bug #663 Fix for `PATH` separator in `BaseNodeFilter` (Ivan Nikolić)

This PR was merged into the 1.2-dev branch.

Discussion
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Fix for `PATH` separator in `BaseNodeFilter`

Make it platform agnostic with `PATH_SEPARATOR`.

Commits
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e89f9ca Fix for `PATH` separator in `BaseNodeFilter`