open.mp compatibility

[blefony]

@IllidanS4 Hi! The release of open.mp is getting closer. This will not have YSF support, since it already includes many features from it. But I'm sure some will not. So I suggest creating a branch or a separate repo to rewrite the YSF plugin for open.mp, where working things will gradually be added and there will be no incompatibilities. You can name the plugin differently if necessary. Thanks.