2.0.0-beta2

Second beta release.

• (ADD) Add UTF-8 support in Alpha, Alnum, Strlen*, and Word filters with help from @mivanov93.
  • All string-length filters are now multi-byte aware using either mbstring or iconv extensions.
  • In alnum and alpha rules, use unicode letters and digits instead of ctype.
  • In word rules, use unicode letters and digits instead of \w and \W.
• (ADD) More robust email validation based on is_email() from @dominicsayers, plus IDN support as suggested by @dg via the intl extension.
• (TEST) Update Travis-CI config to use containers.
• (DOCS) Update relevant documentation.