don't compile if XML files already present

See #322, release log:

• 5a7b040 by @yegor256: #322 compile fixed
• 3b97cb5 by @yegor256: #322 parse and optimize fixed
• 6720d30 by @yegor256: chinese
• 656029b by @yegor256: russian unicoe
• 14bdfd5 by @yegor256: data formats
• 6de0d0a by @yegor256: more about decorator
• eeabc74 by @yegor256: no travis

Released by Rultor 1.70.6, see build log