Move OPERATOR_METHODS to module Util.
Extract module IgnoredNode from class Cop.
Simplify handling around re-generation of rubocop-todo.yml.

If the configuration already contains an inherit_from: rubocop-todo.yml,
it must be removed before the file can be generated again. We raise an
error when the condition is detected, but we've done it in a complicated
way.
Split IndentationWidth into IndentationWidth and IndentationConsistency.

Checking two kinds of offences. Should be possible to disable
individually.
Fix rubocop-todo generation bug in SpaceAroundBlockBraces.

The opposite_style_detected and correct_style_detected must only be
called when inspecting code in regard to EnforcedStyle, not the other
style parameters.

Remove unused method SpaceAroundBlockBraces#available_styles. These
values are now taken from the configuration parameter SupportedStyles.
Shave a few lines from ConfigLoader.

Refactor to decrease ClassLength.
Shorten Cop class.

Remove unused method Cop.style?.

Extract private method Cop#buffer_name_matches_any? from Cop#include_file? and Cop#exclude_file?.
Merge pull request #739 from jonas054/shorter_classes_2nd_try

Shorter classes