Debug printing convenience macro

[Tehforsch]

It could be nice having a dbg-like macro that can quickly print a quantity in the desired unit with a call like
qdbg!(vel -> m/s)
which would effectively expand to something like
println!("{} m/s", vel.in_meters_per_second());

Should be easy to implement, if one defines the functional macro from within the procedural macro (which sounds scary, but probably isnt)