initialize first entries on the if_stack to have the correct insn_predicates in case it's immediately popped off

Hashable instructions

See merge request !47

It does not do something fundamentally different than Record.__eq__
and its definition deletes the implementation of __hash__ in python3.

Spill and reload v2

See merge request !21

Make all match objects hashable

See merge request !46

Also make lp.save_and_reload_temporaries.

Change default precompute barrier insn naming

See merge request !45

Conflicts:
	loopy/kernel/creation.py
	loopy/kernel/instruction.py
	loopy/version.py

Only consider predicates with usable inames in predicate hoist selection

See merge request !44