Merge pull request #9 from thierryvolpiatto/master

Fix helm completion
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Use ido completion as default if ido-mode is enabled

This is better than `(featurep 'ido)`.
Merge pull request #10 from syohex/default-completing-type

Use ido completion as default if ido-mode is enabled
Improve helm completing

- Support helm completion if user does not enable `helm-mode`
- Use helm completion as default if user enables `helm-mode`.
Merge pull request #11 from syohex/improve-helm

Improve helm completing
Update document
Bump up version and update Changes