B9PartSwitch v1.4.0 for KSP 1.1.2

Changes

• Find best subtype intelligently
  • If subtype name was previously set, use it to find the correct subtype (allows subtypes to be reordered without breaking craft)
  • If name was not previously set or not found, but index was, use it (this allows transitioning from current setup and renaming subtypes if necessary)
  • If index was not previously set, try to infer subtype based on part's resources (this allows easy transitioning from a non-switching setup)
  • Finally, just use first subtype
• Add unit testing for subtype finding
• Get rid of some unnecessary logging in debug mode
• Refactor part switching a bit