New cop LiteralInCondition
Correct a comment based on feedback from @whitequark
Extract formatter handling logic to FormatterSet
Pass immuatable objects to formatters

This is to avoid mutation of them by any of formatters
when multiple formatters are enabled.
Pass sorted offences to formatters
Use %s format sequence to avoid evaluation of % in a string
Fix CharacterLiteral cop

As @whitequark mentioned in a comment there were a few problems with
this cop:

- characters like ?\n were not properly autocorrected
- characters like ?\C-\M-x should not be flagged since they look pig
ugly in their string form

This fixes both of those problems.
Merge pull request #305 from yujinakayama/refactor-formatter-handling

Refactor formatter handling
New cop BeginBlock
New cop EndBlock
Fix a typo
Fix class comment
Recognize safe assignment in condition (fixes #284)
Handle nested rescues with RescueModifier
Remove unused method Offence#explode
Remove trailing whitespaces
Fix crash in Documentation on empty modules.

Register offence if empty module lacks comment.
Merge pull request #309 from jonas054/fix_documentation_bug

Fix crash in Documentation on empty modules.
New cop DotPosition
Color dots in green in the progress formatter