Adjust content and scroll indicator insets instead of scroll view frame

- Let the scroll view contents scroll behind the transparent iOS keyboard
- Requires no animation, far simpler
Add keyboard distance parameter
Scroll fields to match the keyboard animation
Update comments
Ensure the text view cursor always stays visible
Extract cursor visibility code into its own category
Ensure the most recent cursor position is used
Also ensure that animation occurs when switching between text fields
Only scroll to the first responder for container scroll views

Does not work well with non-container scroll views, e.g. text views
Ensure cursor visibility when entering edit mode in all cases
Make code shorter
Ensure that content and indicators are properly adjusted when the keyboard is displayed

Test with a large text area, e.g. http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_textarea
Fix typo in file name
Make cursor visible when the keyboard is rotated as well
Merge branch 'feature/keyboard-improvements' into develop