Fix a warning in func_integer.inl

The lack of parenthesis triggered -Wshift-op-parentheses in Clang 3.2
Merge pull request #41 from Kangz/0.9.4

Fix a warning in func_integer.inl, issue #41
Fix a bug in glm::perspective() where a degrees-to-radians conversion is being performed twice.
Merge pull request #42 from mackron/perspective-fix

Fix a bug in glm::perspective(). Pull request #42
Added bit interleave for 3 and 4 integers
Merge branch '0.9.4' of https://github.com/g-truc/glm into 0.9.5
Updated unpackHalf2x16 implementation
Merge branch '0.9.4' into 0.9.5