Support Q_PROPERTY highlightNick, nicksCaseSensitive

Upstream commit 17c3921 changed highlightNick and nicksCaseSensitive to use Q_PROPERTY instead of initSet/init.

Quasseldroid should support these instead.

Test case: set to highlight All nicks, case-sensitive true in desktop client. Check highlight settings on Quasseldroid.

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If needed, a full issue will be written later.