Add half-precision floating-point instructions

* Add opcodes-hwacha-pseudo to be produced as well, or else GCC will complain.
Merge branch 'master' of github.com:ucb-bar/riscv-opcodes into confprec
Move half-precision opcodes to opcodes-hwacha-ut
Add line in Makefile to parse confprec
Merge branch 'master' into confprec

Conflicts:
	Makefile
Add vsetprec instruction
Merge branch 'confprec'

Conflicts:
	Makefile