Fix for iOS9

• Adjust Lock
• Closed issues
  • iOS 9 Crash
• Merged pull requests
  • use isUppercase to check if the character is uppercase
  • A key should be able to contain dot
    • use enum as namespace, as Apple does in Combine
    • return early if possible
    • add test testComplex_JSONKeyWithDot_bestMatch
    • [big pr]: refactor project structure