Complete quoting for parameters of some CMake commands

[elfring]

Some parameters (like "${PROJECT_SOURCE_DIR}" and "${DOXYGEN_EXECUTABLE}") are passed to CMake commands in your build scripts without enclosing them by quotation marks. I see that these places will result in build difficulties if the contents of the used variables will contain special characters like spaces.

I would recommend to apply advices from a Wiki article.

[karlrupp]

Thanks for the hint, we will fix this for the next release.

[elfring]

It seems that there are a few more corrections needed in the affected build scripts.

[karlrupp]

Thanks for the comments, I'll integrate your suggestions.

[karlrupp]

I went over the previous changeset and removed the double quotes from all list variables. Thanks for the input, @elfring !

[elfring]

I find that your wording "all list variables" has got a high potential for misunderstandings.
Would you like to improve such a detail a bit more?

[karlrupp]

It's too late now for updating the wording, as I would have to force-push master to do that. From the link to the parent commit and the discussion here on GitHub it should be sufficiently clear from the context what's going on.

[elfring]

I hope that a better understanding will spread more around for CMake developers.

Thanks for your improvement of the build scripts.

[karlrupp]

Well, thank you for bringing the issue up and having a sharp eye for fixing it :-)