Added Function_Turn_movement provider

[Malcolmnixon]

This pull request extracts the turn logic from Function_Direct_movement and moves it into a Function_Turn_movement provider. The benefits of this are:

• Simpler and more modular code
• It's possible to add movement and turning separately
• Movement can be disabled without disabling turning

The only down-side is that existing code will now have to update the Function_Direct_movement settings, and possibly add a Function_Turn_movement to keep existing player movement behavior.

This pull request implements feature request #115

[BastiaanOlij]

Sorry for the late response Malcolm, looks good, my only concern, as you already mention, is that this is a breaking change for people using previous versions of the library. Might not be avoidable, I do like this split.

[Malcolmnixon]

I'll push up an update this evening with the VERSIONS.md updated to mention the change.