Add check for unless to GuardClause

make it configurable how many lines the body of an if / unless needs to
have to not be ignored
Enable GuardClause cop and adapt code
Make `NonNilCheck`'s semantic changes configurable
Merge pull request #1048 from geniou/guard_clause

Add check for unless to GuardClause and make one-line body configurable
Merge pull request #1047 from hannestyden/stabilize-semantics-of-non-nil-check-autocorrect

Stabilize semantics of NonNilCheck autocorrect
Fix up typos in default.yml

Fix:
 * 'and' -> 'an'
 * 'alignes' -> 'aligns'
 * 'indenation' -> 'indentation'
 * 'separat' -> 'separate'
 * 'interation' -> 'iteration'
Merge pull request #1053 from kevinjalbert/patch-2

Fix up typos in default.yml
Improve LineEndConcatenation's message
[Fixes #1050] Rename rubocop-todo.yml file
Merge pull request #1055 from geniou/rename_todo_file

Rename rubocop-todo.yml file to .rubocop_todo.yml
New cop UnneededPercentX

Part of #835.
Merge pull request #1056 from jonas054/unneeded_percent_x

New cop UnneededPercentX