cudev is used for new device layer

- new reduce implementation (with kepler optimizations)
- saturate_cast via asm command
- video SIMD instructions in element operations
- float arithmetics instead of double
- new deviceSupports function

update gpu tests

added convert functions to BruteForceMatcher_GPU
other minor fixes

fixed BFM warning ("cannot tell what pointer points to")

removed test whether z is negative in gpu::solvePnpRansac (there is no need in this for tests passing)