Macro decl_traces

macro_rules! decl_traces {
    ($name:ident; $($checkpoint:ident),+) => { ... };
}

Declare traces group.

Creates a module with the passed $name.

**Note:**Traces are stored locally for each thread (thread_local).

Module exposes two main methods:

• fn start_tracing() - Simply calls take_traces() and discards the result, in order to clean up old traces.
• fn take_traces() - Take accumulated traces.