fixed possible endless recursion when trying to create a UNIX style path on Windows

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branch : 0.9
::create() has its own, dedicated exception with a much more helpful text; so let's use it here

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removed explicit version from composer.json

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Added tag v0.9.0-alpha2 for changeset 9b66ef3573be

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re-added the explicit version

Sally uses this key to determine its own version and the addOn compatiblity.
Until we find another way to embed the version somewhere, we have to live with
it being put in here.
This does not affect the other sally apps.

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branch : 0.9
another 0.9.0-alpha2

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back to dev

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branch : 0.9
Moved tag v0.9.0-alpha2 to changeset 5c83b80aee53 (from changeset 9b66ef3573be)

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branch : 0.9