Revive is fast, configurable, extensible, flexible, and beautiful linter for Go. Drop-in replacement of golint.

This is part2 of fixes for problems found for following set of rules:

• [rule.if-return]
  • Redundant if when returning an error. -> Checking if an error is nil to just after return the error or nil is redundant.
• [rule.increment-decrement]
  • Use i++ and i-- instead of i += 1 and i -= 1. -> By convention, for better readability, incrementing an integer variable by 1 is recommended to be done using the ++ operator. This rule spots expressions like i += 1 and i -= 1 and proposes to change them into i++ and i--.
• [rule.var-declaration]
  • Reduces redundancies around variable declaration. -> This rule proposes simplifications of variable declarations.
• [rule.package-comments]
  • Package commenting conventions. -> Packages should have comments. This rule warns on undocumented packages and when packages comments are detached to the package keyword. More information here
• [rule.receiver-naming]
  • Conventions around the naming of receivers. -> By convention, receiver names in a method should reflect their identity. For example, if the receiver is of type Parts, p is an adequate name for it. Contrary to other languages, it is not idiomatic to name receivers as this or self.
• [rule.unexported-return]
  • Warns when a public return is from unexported type. -> This rule warns when an exported function or method returns a value of an un-exported type.
  • Few findings left untouched -> for some deeper review in the future.

For changed files, minor fixes were also made (got rid off "log" package where it was easy, CamelCase instead of snake_case, etc...)