Golang liibrary for case convertion of string.

1. go get -d github.com/pinzolo/casee.
2. Add github.com/pinzolo/casee to import section in your go file.

• ToSnakeCase
  Convert to snake_case style string.
• ToChainCase
  Convert to chain-case style string.
• ToCamelCase
  Convert to camelCase style string.
• ToPascalCase
  Convert to PascalCase style string.
• ToFlatCase
  Convert to flatcase style string.
• ToUpperCase
  Convert to UPPER_CASE style string.

• IsSnakeCase
  Check argument string is snake_case.
• IsChainCase
  Check argument string is chain-case.
• IsCamelCase
  Check argument string is camelCase.
• IsPascalCase
  Check argument string is PascalCase.
• IsFlatCase
  Check argument string is flatcase.
• IsUpperCase
  Check argument string is UPPER_CASE.

If first character is digit, IsCamelCase, IsPascalCase and IsFlatCase always returns false.
Because cannot judge upper or lower.