v2.0.0

NECST v2.

To mark this version, just in case reflections of backup scripts and other developments hereafter introduce new bugs.

• backup: From on-site PCs, taken on Mar. 2020.
• Tag and version have changed from v1.0.0 to v2.0.0 on Nov. 18, 2021 due to revision of confusing versioning rule.