Graph protocol

• Separates node from graph types for increased flexibility.

Empty path

Gives back an empty array if no path is found like described in #7

Capital A*

• This version is not backwards compatible with version 1.x.x because the module name was changed to start with a capital letter.
• Changed iOS deployment target to 10.0

Fix iOS target & Playground

• Resolves problems within the xcode project that caused the iOS target to malfunction.
• Updated code in the playground that cause some errors.

SPM Support

The first version with a Package.swift file