Add support for callable form validation rules
Fix #2928
Re-enable hhvm/mysqli tests
Fix #2928, #2929
Check image path is include http:// or https://
Merge pull request #2934 from wuwx/patch-3

Check image path is include http:// or https://
Add support for protocol-relative URLs in HTML helpers img(), link_tag()
Partially revert PR #2190

The core shouldn't depend on constants that are not defined by itself
Image_lib - minor corrections on some comments.
Merge pull request #2936 from ivantcholakov/develop

Image_lib - minor corrections on some comments.
Removed the requirment of quantity to trigger cart update.
Added missing semicolon
Fixed filemtime
Fixed coding style & line length.
Merge pull request #2939 from aanbar/cart_update

Removed the requirement of quantity to trigger cart update.
Added changelog entry.
Updated changelog.
Merge pull request #2940 from aanbar/zip_mtime_fix

Fixed issue with _get_mod_time
No start tag (<p>)
Making highlight_phrase() to be UTF-8 compatible on demand.