Changed style to reflect consensus that parens should surround single-line lambdas
Rewrote type inference paragraph, to encourage explicit types for public APIs
Strengthened language against postfix operators in the style guide
Added a paragraph in the style guide to explain the performance penalty for structural types
Modified the parentheses style paragraph to mention disabling semicolon inference
Removed the style reference to the pipeline operator
Fixed typos
Some minor style fixes suggested by Seth Tisue
Merge pull request #215 from kenbot/master

Style guide updates