RsXslt is not caching factories

See #1146, release log:

• a339adc by @yegor256: #1146 versions up
• 60b8477 by @yegor256: #1146 fresh qulice
• 139e297 by @yegor256: #1146 cache XSL factories
• 3789ae3 by @yegor256: #1071 better explanation

Released by Rultor 2.0-SNAPSHOT, see build log