Add a "cfg_postorder:" printout to the "test domtree" file tests and use
that to check the computed CFG post-order instead of doing it manually
with Rust code.
* Function names should start with %
* Create FunctionName from string
* Implement displaying of FunctionName as %nnnn with fallback to #xxxx
* Run rustfmt and fix FunctionName::with_string in parser
* Implement FunctionName::new as a generic function
* Binary function names should start with #
* Implement NameRepr for function name
* Fix examples in docs to reflect that function names start with %
* Rebase and fix filecheck tests
This affects the comparison instructions which now read "icmp ult a, b".
This mimics LLVM's style and makes it simpler to add instruction flags
in the future, such as "load v1" -> "load aligned v1".
These enumerated operands and flags feel like opcode modifiers rather
than value operands, so displaying them differently makes sense.
Value and numeric operands are still comma separated.
This test runs the verifier on each function and matches the resulting
verifier error against the "error:" annotation.
Move the existing verifier test into filetests/verifier/ and use the new
syntex.
