Windows no context switch to ignore symbolic and hard links

[meowcatluke]

if hashing recurive directories in windows there is no contect argument to not follow symbolic and hard linkss.

[lxp]

Windows is currently not officially supported in the 3.0.0 release (see changelog here: https://github.com/cfv-project/cfv/releases/tag/v3.0.0).
Before picking up this feature request, it is necessary to get the test suite working on Windows and add back Windows support.
If anyone is interested to help out here, take a look at the following issue first: #24