add landscape-x theme

[HipHopCoderS]

Check List

Please read and check followings before submitting a PR.

• [x] I want to publish my theme on Hexo official website.
  • [ x] I have read the theme publishing doc.
  • [x] name is unique.
  • [x] link URL is correct.
  • [x] preview URL is correct.
  • [x] preview URL web site is rendered correctly.
  • [x] Add a screenshot to source/themes/screenshots.
  • [x] Screenshot filename is same as value of name.
  • [x] Screenshot size is 800 * 500.
  • [x] Screenshot file format is png.
• [ ] I want to publish my plugin on Hexo official website.
  • [ ] I have read the plugin publishing doc.
  • [ ] name is unique.
  • [ ] link URL is correct.
• [ ] Others (Update, fix, translation, etc...)
  • Languages:
  • [ ] en English
  • [ ] ko Korean
  • [ ] pt-br Brazilian Portuguese
  • [ ] ru Russian
  • [ ] th Thai
  • [ ] zh-cn simplified Chinese
  • [ ] zh-tw traditional Chinese