Add ClassAndModuleChildren cop

Checks nested or compact style for children classes and modules.
Fix offenses reported by ClassAndModuleChildren
Remove trailing spaces in yaml files
Fix alignment of concatenated strings
Merge pull request #869 from geniou/nested_style

Add ClassAndModuleChildren cop
add example to explain hang while auto correct
fix hung while auto correct
Accept non-rb extensions and file names specified in AllCops/Includes

https://github.com/bbatsov/rubocop/commit/a0064f7ddd46573e8f59deda317403e880239f53#commitcomment-5664681
Merge pull request #873 from hiroponz/bug-hung-auto-correct

Bug hang auto correct
Merge pull request #874 from yujinakayama/relax-filename

Relax Filename cop
Bump version to 0.19.0
Correct release notes
Add missing release date to the changelog
Prevent mutliple cli options that result in exit(0) being specified at once