IE11 User Agent support added
Enable HHVM on travis-ci
Dont break the build if tests only fail on HHVM
Merge pull request #2819 from fredemmott/hhvm-travis

Enable HHVM on travis-ci
Fix incorrect checks for the fwrite() return value

! fwrite() could trigger false-positives as it is possible for it to return 0
instead of boolean FALSE. (issue #2822)

Also removed an unnecessary log level check that caused an extra space to be inserted
for the INFO level. (proposed in PR #2821)
CI_URI changes related to the 'permitted_uri_chars' setting

 - Initialize and cache the value in the class constructor instead of searching for it every time
 - Removed the preg_quote() call from _filter_uri() to allow more fine-tuning from configuration
 - Renamed _filter_uri() to filter_uri() - it was public anyway and using it cannot break anything

Related: issue #2799
Trident prefix added to avoid potential false positives.
Merge pull request #2811 from dionysiosarvanitis/fix/ie11_user_agent

IE11 User Agent support added
Fix #2822: Incorrect usage of fwrite()

We only used to check (and not always) if the return value of fwrite() is boolean FALSE,
while it is possible that the otherwise returned bytecount is less than the length of
data that we're trying to write. This allowed incomplete writes over network streams
and possibly a few other edge cases.
Fix #2799 by adding conditional PCRE UTF-8 support to CI_URI::filter_uri()

Also did a tiny micro-optimization in the Utf8 class.