Increase maximum for zoom plugin

[meisenzahl]

Closes #876

[danirabbit]

Hey thanks for working on this!

I’m not sure this really needs to be configurable. The user already configures their zoom level as they use the feature. So it would probably be more immediately useful to add more steps without any configuration

[meisenzahl]

@mmohsinkhan has described that he needs at least a zoom factor of 6.0f. Should the maximum then be even higher, e.g. 10.0f? Should the step size still be 0.5f?

[mmohsinkhan]

Max magnification factor 2.5f set currently is not enough for people like me. I need to magnify desktop more than 2.5 times to make it usable for me.
I don't think setting max factor to 10f would do any harm, on the bright people like me would be able to use Elementary out of the box.

Thanks

[danirabbit]

This looks good to me! Seems to work as expected. Thanks for creating this pull request.

I have one tiny inline suggestion while we're here. It might be nice to have a little bit of feedback when we reach the limit :)

[danirabbit]

Perfect! Thanks for fixing this :)

[meisenzahl]

The solution was much easier than I thought #Bitesize

[mmohsinkhan]

Thanks guys for the support.