Do not perform autofocus is flip occurs in less than x minutes

[Yannick Dutertre]

I noticed that it is possible for autofocus to prevent the mount from flipping, by holding off the flip until after the time to flip becomes 23+ hours and the ShouldFlip method stops reacting to it.

This is more likely with slow computers and with the new autofocus PR, which with reattempts and frames per focus point, could take several minutes.

Need to add a condition in the ShouldAutofocus function to check whether time to meridian is less than, say, 10 minutes. If less than that, return false.