Add some units

[triallax]

No description provided.

[triallax]

I want to use 1.75 inch, but this causes cargo run --example=inspect to fail (even when I have use si::imperial):

    Finished dev [unoptimized + debuginfo] target(s) in 0.27s
     Running `target/debug/examples/inspect`
thread 'main' panicked at numbat/examples/inspect.rs:11:66:
called `Result::unwrap()` on an `Err` value: TypeCheckError(UnknownIdentifier(Span { start: SourceCodePositition { byte: 3266, line: 117, position: 30 }, end: SourceCodePositition { byte: 3270, line: 117, position: 34 }, code_source_id: 16 }, "inch", None))
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::result::unwrap_failed
   3: core::result::Result<T,E>::unwrap
             at /builddir/rust-1.74.0/library/core/src/result.rs:1077:23
   4: inspect::main
             at ./numbat/examples/inspect.rs:11:19
   5: core::ops::function::FnOnce::call_once
             at /builddir/rust-1.74.0/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[eminence]

Maybe there's a problem with a circular dependency: imperial.nbt depends on misc.nbt, so adding a dependency from misc.nbt back to imperial might cause a problem?

[sharkdp]

Maybe there's a problem with a circular dependency

That's it. We currently 'tolerate' cyclic dependencies:

numbat/numbat/src/resolver.rs

Lines 263 to 275 in cb1c6be

	#[test]
	fn resolved_cyclic_imports() {
	let program = "
	use cycle_a
	";
	let importer = TestImporter {};
	let mut resolver = Resolver::new(importer);
	let program_inlined = resolver.resolve(program, CodeSource::Internal).unwrap();
	assert_eq!(&program_inlined, &[]);
	}

But we should probably show an error instead.

[sharkdp]

For this PR, let's go with what you have, @mhmdanas. Another option would be to split this module into multiple pieces. But we can do this in a follow-up.

[sharkdp]

Thank you