Update README.
Update Manifest.
Write basic selected state save and restore logic.
Issue #1 Implement previous selection management feature.

- use localStorage
- refactor.
Enhance .gitignore.
Merge branch 'feature/1-remember-previous-selection' into develop
Issue #7 Choose MIT License.
Issue #10 Update README and export CHANGELOG.md partry.
Fix en typo and change layout.
Issue #4 Fix Windows font size and specify font explicitly.
I18N read attribute bug fix.
Update README.
Update README.
Add chrome store release utility script.
Merge branch 'develop'

v0.7.0 release.