Bugfix in min/max of vex::vector<non-double>
Better hunting for OpenCL, VexCL

We now configure fine, hands-free, against the ICES Sysnet modules
Fix "make check" on systems with 32-bit-only GPUs
Bugfix for raw_value_type<Eigen stuff>
Use raw_value_type for scalars

This fixes vex::vector<float> runs on single-precision-only GPUs