allow topic to be encapsulated in quotes

[bodeme]

[ ] Have you signed the Eclipse Contributor Agreement, using the same email address as you used in your commits?

• Do each of your commits have a "Signed-off-by" line, with the correct email address? Use "git commit -s" to generate this line for you.
• If you are contributing a new feature, is your work based off the develop branch?
• If you are contributing a bugfix, is your work based off the fixes branch?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run make test with your changes locally?

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Also created this fix based on the develop-branch with slightly changed calls (REQUIRE_NON_EMPTY_OPTION, mosquitto_malloc with one underscore)

[bodeme]

Fixes #1756
Fixes #658