Fix VariableTable#find_variable_entry behavior if current scope is block

If current scope is block, the method was looking for all outer scope
variables even if the direct outer scope is not block.
Add missing utf-8 encoding comment
New cop WhileUntilDo

The cop tracks uses of `do` in multi-line `while/until` statements.
Break into categories and sort them alphabetically
Fix a broken spec
Set config in all cop classes before inspect is called.

Also restore spec "runs just one cop if --only is passed" to previous.
Merge pull request #300 from jonas054/fix_config_nil

Set config in all cop classes before inspect is called.
Add missing encoding comment
Code style
Handle arrays with character literals in WordArray.

For example [?\r, ?\n] caused a crash. Now treated as an offence.
Add new cop CharacterLiteral
Merge pull request #301 from jonas054/fix_word_array

Handle arrays with character literals in WordArray.
Migrate Loop cop to Parser 2.0.0.beta8

Now Parser generates `while_post` and `until_post` nodes for
`begin...end while/until` source.
So we just need to catch them.
https://github.com/whitequark/parser/commit/679b526
Migrate BlockNesting cop to Parser 2.0.0.beta8

We need to catch the newly added `while_post` and `until_post` nodes.
Migrate RescueModifier cop to Parser 2.0.0.beta8

Parser now generates `kwbegin` node for explicit `begin end` source
to differentiate it with implicit begin.
https://github.com/whitequark/parser/issues/70#issuecomment-19525402
Revert "Mark a spec as broken with Parser 2.0.0.beta6"

This reverts commit 71e4067214f60f917509cd0362d1d60dce37e91e.
Update Parser dependency to 2.0.0.beta8
Merge pull request #302 from yujinakayama/migrate-to-parser-2.0.0.beta8

Migrate to Parser 2.0.0.beta8
New cop EndInMethod
Remove 2 pending from specs and fix lib code to make specs pass.