This commit improves the bot detection regex by:

  - adding a number of missing strings, such as alexa, facebookexternalhit, feedburner, nagios, postrank, pingdom, slurp, and yahoo!
  - removing redundant strings such as googlebot and robot (redundant because of the inclusion of a general "bot" string)
  - consolidate similar strings ("crawler" and "crawling" became "crawl(er|ing)")
  - alphabetize the list of bots

To generate previews on the fly, Google uses the user-agent "Google Web Preview" (the fully-qualified user-agent you see in your server logs may change from time to time) to render images on demand. This commit adds "google web preview" to the bot detection regex.

This commit adds "yandex" to the list of bots, to detect the popular Russian search engine.

This commit improves the bot detection regex by:

  - adding a number of missing strings, such as alexa,
    facebookexternalhit, feedburner, nagios, postrank, pingdom, slurp,
    and yahoo!
  - removing redundant strings such as googlebot and robot (redundant
    because of the inclusion of a general "bot" string)   - consolidate
    similar strings ("crawler" and "crawling" became "crawl(er|ing)")
  - alphabetize the list of bots

To generate previews on the fly, Google uses the user-agent "Google Web
Preview" (the fully-qualified user-agent you see in your server logs may
change from time to time) to render images on demand. This commit adds
"google web preview" to the bot detection regex.

This commit adds "yandex" to the list of bots, to detect the popular
Russian search engine.