Add onSetPosition callback

Consider adding a callback for setPosition.  I've used this to move buttons and dots based on slide contents/heights.
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fix  RTL drag and swipe #674
Fixes #760

Also adds non animated slickGoTo
Fixes #685
Fixes #691
Merge pull request #765 from rollstudio/master

fix RTL drag and swipe #674
Merge pull request #495 from avr/patch-1

Add onSetPosition callback
Fixes #740
Fixes #673
Fixing loop shenanigans
Version bump
merge