Fix for extending classes in a subdirectory (e.g. drivers)
Add mimes pdf application/force-download
Prevent email header injection

When a header is set, newline characters are stripped so one cannot inject his/her own email header(s). Since set_header is only used to set one header at a time, it should have no effect on any code relying on this function
added newlines to end of email header when send_multipart === false
Add support for https behind a reverse proxy using X-Forwarded-Proto
Change True -> TRUE per codeigniter guidelines
fixed typo in guide/lib/xmlrpc.rst

$size = $parameters[1]['shape'];
replaced by:
$shape = $parameters[1]['shape'];
Merge pull request #2479 from ckdarby/develop

Fixes #2340
Merge pull request #2484 from chrisege/develop

added newlines to end of email header when send_multipart === false
Merge pull request #2492 from nonchip/develop

fixed typo in guide/lib/xmlrpc.rst
Merge pull request #2403 from groovenectar/loader-fix

Fix for extending classes in a subdirectory (e.g. drivers)
Use codeigniter coding style
remove newline in system/core/Common.php
Added X-Forwarded-Proto support to changelog
remove newline at eof in syste/core/Common
Force the file extension to lower case
Revert "remove newline at eof in syste/core/Common"

This reverts commit 7061bd014b6b7dbf89bf42e940aa134228f044ce.
fix indentation according to codeigniter codestyle system/core/Common
remove newline again in system/core/Common.php, silly editor keeps adding it
remove else clause in is_https function, just add return FALSE as fallback