Collapse raw_reference_cast.h & raw_reference_cast.inl
Reorder the code therein such that raw_reference_cast's definitions occur after various template specializations it instantiates

Fixes #600
Merge branch '1.8.0' of github.com:thrust/thrust into issue-600
Merge pull request #602 from jaredhoberock/issue-600

Issue 600
Merge pull request #603 from thrust/1.8.0

1.8.0