Fix state leak in Cop.all

Cop.all now returns a copy of the collection that holds all the cops.
This way modifications to it won't affect the global state.
Merge pull request #335 from edzhelyov/fix-leaky-state-of-cops-all

Fix state leak in Cop.all
Check not node in LiteralInCondition

Like the existing and/or check this is flawed, but will be improved upon soon.
Bump Parser dependency to 2.0.0.pre1
Make the DotPosition cop configurable

It now has a `Style` config which can have one of two values -
`leading` (the default) and `trailing`.
Correct the behavior of LiteralsInCondition

As @whitequark had correctly observed the logical expressions in the
condition had to be checked recursively for literals.
Bump version to 0.9.1
Change encoding cop to accept utf comment by magic_encoding gem
Merge pull request #336 from onemanstartup/encoding_cop

Change encoding cop to accept utf comment by magic_encoding gem
Work with absolute Excludes paths internally.

This solves the problem with excluding a directory tree that contains
.rubocop.yml files. Those configurations would get Excludes from a
higher level, let's say ../../vendor/**, but when comparing relative
file paths to those patterns they would not match.
Merge pull request #337 from jonas054/fix_excludes

Work with absolute Excludes paths internally.
Improve TrivialAccessors cop

* class attributes are also detected
* trivial readers are required to have no arguments
* refactored code a bit
* TrivialAccessors now accepts a config option `ExactNameMatch` that
  controls the rigidness of the checks performed

This fixes #308.
Fix broken spec
New cop RedundantReturn (#60)
New cop RedundantBegin
Remove some dead code