Refs #1301 -- moved constant time code into it's own .c and .h files
Simplify, thanks @dstufft
Fix?
Added include guards, and license headers
Revert "Added include guards, and license headers"

This reverts commit a4902b67fb4ef1e7fd477d27353242da879ca90c.
Added back license headers
Merge pull request #1302 from alex/move-to-files

Refs #1301 -- moved constant time code into it's own .c and .h files