Use animationDuration for transition animation duration

[ChaosCoder]

Description

This uses the already existing animationDuration to animate when a primary or drawer view controller changes instead of hardcoding it to 0.5.

This alters the behavior, as the default animationDuration is set to 0.3, but the hardcoded value was set to 0.5. As this is only a cosmetic change, I would argue that it does not break previous behavior.

If you would like to introduce a new property for it instead of reusing the (then poorly named) animationDuration, I would be happy to get name suggestions.

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• My code follows the style guidelines of this project
• My code does not break backwards compatibility with earlier versions of PulleyLib
• My code is fully functional with all supported device sizes and orientations
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have checked that my code does not break the behavior of the Sample/Demo app
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have tested and can prove my fix is effective or that my feature works