Don't scroll while setting the text, attributedText, selectedRange or selectedTextRange

This was causing unwanted animations that conflicted with my own. The
way I see it, when I’m manually setting the text I don’t want any
automatic animations, and I can trigger those manually if I need them.
Merge pull request #1 from steipete/master

Update from steipete:master
Allow scroll changes on setSelectedTextRange:

Oops. setSelectedTextRange: is used by UITextView to update the
selection based on used input.
Merge pull request #9 from hpique/master

Don't scroll while setting the text or selection manually