Refactor for optimization

[fktn-k]

In this PR, some refactorings have been made for better performance, including:

• cleaning up basic_node's destructor
• optimizing the process of scanning multiline scalars
• improving the scanning of scalar contents for type detection

Also, the Make target for benchmarking contains a wrong fixed path and performance of debug builds were not correctly measured.
However, the performance of debug builds seems to need some more work for trustworthy results, which is why the performance data of debug builds have been removed (possibly revoked in the future).

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Pull Request Checklist

Read the CONTRIBUTING.md file for detailed information.

• Changes are described in the pull request or in a referenced issue.
• The test suite compiles and runs without any error.
• The code coverage on your branch is 100%.
• The documentation is updated if you added/changed a feature.

Please don't

• The C++11 support varies between different compilers and versions. Please note the list of supported compilers. Some compilers like GCC 4.7 (and earlier), Clang 3.3 (and earlier), or Microsoft Visual Studio 13.0 and earlier are known not to work due to missing or incomplete C++11 support. Please refrain from proposing changes that work around these compiler's limitations with #ifdefs or other means.
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• Please do not open pull requests that address multiple issues.

[github-actions]

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Coverage data has been uploaded for the commit e28350d24a7256c1f24c27d79c7e52b98124a5d4.
You can download the artifact which contains the same file uploaded to the Coveralls and its HTML version.

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[coveralls]

Pull Request Test Coverage Report for Build 9382922992

Details

• 82 of 82 (100.0%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 99.98%

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Totals
Change from base Build 9340106021:	-0.02%
Covered Lines:	3888
Relevant Lines:	3888

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💛 - Coveralls

[coveralls]

Pull Request Test Coverage Report for Build 9384349256

Details

• 82 of 82 (100.0%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 9340106021:	0.0%
Covered Lines:	3888
Relevant Lines:	3888

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💛 - Coveralls