Allow increment of hour and minute

This pull request makes it possible that you only select minute quarters.
It allows you to set the the incremental step size for hours and minutes.
So for example if you set hourstep = 2, then you can only select even hours. minutestep = 5 and you can only select minute 5, 10, 15 etc.

Also fixed that AM/PM was not shown on initializing of the hourview (only after toggling am/pm)