Complete 3.0 upgrade notes about NULL returned on missing items
Add windows filename rule as an option for upload files
Revert "Add windows filename rule as an option for upload files"

This reverts commit 23719ab569c9c8d6b791f65d7861daba3895ddcb.
Make the bad filename array public in Security library
Rename bad chars property to filename_bad_chars, remove the setter and add changelog entry
[ci skip] Alter a changelog line
Fix #2501 & another -related bug
Fix #2585
Various typos and tabs adjustments
Replace php_sapi_name() function with PHP_SAPI constant

exact same behavior but faster, shorter
Fix noneffective static variable cache in log_message()
An improved version of PR #2584, fixes #2583
Add a changelog entry for PR #2590 and further optimize log_message()

CI_Log::write_log() already checks the log threshold, so there's no point in doing it in log_message() as well.