Update unit test.
Add `dom` module.
Add unit test for `dom` module.
Add `action` module.
Update building script.
Merge pull request #6 from zpbx/dev

Add `root` module.
Merge pull request #7 from zpbx/dev-test

Update unit test.
Merge pull request #8 from zpbx/dev-dom

Add `dom` module.
Merge pull request #9 from zpbx/build

Update building script.
Update `str` module and its unit tests.
Update `action` module and its unit tests.
Merge branch 'dev-str' into dev-action

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Update `action` module and its unit tests.
Add some comments in test code.
Improve getting body element.
Merge pull request #10 from zpbx/dev-str

Update `str` module and its unit tests.
Rename some variables in `dom` module.
Merge pull request #11 from zpbx/dev-action

Add `action` module.
Merge branch 'master' into dev-dom-var

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Adapt usage in `action` module.