Add return type for view loader.

When _ci_return is TRUE.
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