let's rename "data" to something less visible

See #208, release log:

• 8be588c by @yegor256: merge
• 601aa55 by @yegor256: #208: renamed
• 4d77f05 by @yegor256: #208: Datarized
• 5cc751f by @nlchar: splitted tests for int.pow for...
• 4903f2d by @nlchar: Merge remote-tracking branch '...
• aec5c24 by @nlchar: fixed and covered the zero pow...
• 895e295 by @nlchar: Added the Error object to the ...
• f5fe213 by @nlchar: WIP fix for int.pow zero raise...
• 774c58c by @nlchar: Merge remote-tracking branch '...
• 775d976 by @nlchar: typo fix
• 7ae4d65 by @nlchar: mapi and map array mutation is...
• 734061a by @yegor256: Merge pull request #197 from n...
• 427fa61 by @nlchar: fixed run.sh and run.cmd to ac...
• fb1a59f by @yegor256: Merge pull request #194 from n...
• c3bd712 by @nlchar: Fixed iteration example in REA...
• c312d96 by @yegor256: sandbox fixed

Released by Rultor 1.69.1, see build log