Added a test for the `xz` program path on Cygwin
Fixed the `xz` program path on Cygwin
bug #68 Fixed the `xz` program path on Cygwin (alquerci)

This PR was merged into the 1.1-dev branch.

Discussion
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| Q               | A
| --------------- | ---
| Bug fix?        | yes
| New feature?    | no
| BC breaks?      | no
| Deprecations?   | no
| Tests pass?     | yes
| Related tickets | #65
| License         | GNU GPLv3

Commits
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7396dca Fixed the `xz` program path on Cygwin
ad0bb6a Added a test for the `xz` program path on Cygwin