Add return type for view loader.

When _ci_return is TRUE.
re-fixes #2637
delimiter used for regex bounds found in neg. lookahead
causes error using @ delimiter now for this expression
Merge pull request #2669 from DaveMC08/feature/re_fixes_2637

re-fixes #2637
partial fix #2667
this fixes the ability to replace a space with a /
and skip the XSS filtering
parse $extra attributes in form_dropdown.
Merge pull request #2671 from aanbar/develop

parse $extra attributes in form_dropdown.
Merge pull request #2670 from DaveMC08/feature/issue_2667

partial fix #2667
Exra bmp mimes

Mimies source http://filext.com/file-extension/BMP
Update user_agents.php

Add detection for Opera 16
Merge pull request #2676 from Jcchemin/patch-1

Update user_agents.php
Merge pull request #2672 from stgeneral/patch-1

Exra bmp mimes
Merge pull request #2668 from garthkerr/patch-1

Add return type for view loader.
Fix #2682
Fix #2674