Makefile: Fix warning

Meant to include imageresampler, didn't need to, included it wrong anyways.
Fix enum mismatch warning
Clean up some overconst
Add <functional> and namespacing for std::less<>
Init initializer list in declaration order

Fixes a minor GCC warning
Down to 1 -Wall warning
Merge pull request #3 from rsaxvc/master

GCC and Warning fixes