The script is halted and a '500 Internal Server Error' is issued when a fatal error occurs.

Signed-off-by: Jesse van Assen <jesse.v.assen@gmail.com>
Complete 3.0 upgrade notes about NULL returned on missing items
Optimize CI_Session::__construct() routines and make driver validity check stricter
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
Merge pull request #2575 from wmh/filename_rule

Add windows filename rule as an option for upload files
[ci skip] Alter a changelog line
Merge pull request #2566 from vlakoff/develop

Complete 3.0 upgrade notes about NULL returned on missing items
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
Merge pull request #2586 from vlakoff/develop

Various typos and tabs adjustments
Fix noneffective static variable cache in log_message()
An improved version of PR #2584, fixes #2583
Merge pull request #2590 from vlakoff/develop

Fix noneffective static variable cache in log_message()
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.
[ci skip] Add MD5 checksums to download page (rel: #991)