Partial config matching

[yonaskolb]

This makes 2 changes to how configs are referenced and applied in Settings (in project settings, target settings, setting groups)

• partials are matched
• matches are case insensitive

This means you can apply settings in a wider way.

For example you can do the following:

configs:
  Test Debug: debug
  Staging Debug: debug
  Production Debug: debug
  Test Release: release
  Staging Release: release
  Production Release: release
settings:
  configs:
    test: # applies to both Test Debug and Test Release configs
      BUILD_SETTING: test
    debug: # applies to all debug configs
      OTHER_BUILD_SETTING: debug setting

This also adds some missing validation in the spec validator