support literal boolean in ifelse condition

[jlapeyre]

Currently this importer supports tests on classical registers as the condition in conditionals. It seems that only if-else statements effecting dynamics circuits are supported.

But the OC3 spec includes if (true) { ... in examples. This is not difficult to implement. It would be useful, not least for testing thing such as scopes. But it's a bit narrow. Maybe some other cases of expressions that evaluate to a bool at compile-time would not be difficult either.