proof of concept

See #1, release log:

• 109b21c by @yegor256: #1 typo
• 3f43ad4 by @yegor256: #1 rultor cfg
• d05c9e4 by @yegor256: #1 push to codecov
• 1da212f by @yegor256: #1 jacoco
• 241bedb by @yegor256: badge off
• 1198c5c by @yegor256: travis cfg
• b48592e by @yegor256: doc
• c7d771b by @yegor256: #1 docker pull
• 612d46f by @yegor256: #1 TkIndex
• e178032 by @yegor256: #1 xsl
• a6ae25f by @yegor256: #1 restriction removed
• 4449324 by @yegor256: logo
• 6369ef9 by @yegor256: nubs
• 8ff97bd by @yegor256: doc
• 6968ce0 by @yegor256: #1 xsl
• d2545c9 by @yegor256: #1 ttl
• f6fc23a by @yegor256: #1 lowercase
• 55fca70 by @yegor256: #1 layout
• 6b32eb1 by @yegor256: #1 docker for mysql
• e966588 by @yegor256: doc
• and 73 more...

Released by Rultor 1.66.2, see build log