Add min, max, and order to std::ops

Realized that one can add those to std::ops. Closes #246 (closed)

• Pro: does not clog the name space
• Con: it may not be possible to rely on type inference for different lengths (or as part of the more advance type inference system?), but I guess it is possible to make them __builtin__ later?

Also added the operation order which orders the two inputs in increasing order. Useful to build sorting networks etc.

No testbench as my Verilog sucks...

Author checklist

• New Diagnostics have at least one snapshot test that triggers it
• Added a line to CHANGELOG.md, if relevant