Variable manager: Provide file path variables with native separators
Variable manager: Provide file path variables with native separators

Since we cannot know if the path should be represented with native
separators or not, we have to leave the decision to the user, by
providing separate variables for it.

Change-Id: I4d06d0a29627f4e82f8b2c7acac06f442c5c5eb4
Task-number: QTCREATORBUG-11896
Reviewed-by: Daniel Teske <d8a411aec9a206efedb4d45b75fe8d13f1e2b628@theqtcompany.com>

martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator