modify pattern code style
a trivial change
correct attributes grammar
correct declarations  grammar
modify [a swift tour] code style
fix 2.1 the basics
fix 2.2 basic operators
fix 2.3 Strings_and_Characters
fix 2.4 Collection_Types
fix 2.5 Control_Flow
fix 2.5 Control_Flow(2)
fix 2..6 Functions
fix 2.7 closures
fix 2.7 closures(2)
fix 2.8 Enumerations
fix 2.9 classes and structures
fix 2.9 classes and structures
fix 2.10 properties
Merge branch 'develop' of https://github.com/stanzhai/the-swift-programming-language-in-chinese into develop
fix 2.11 methods