Various improvements

[jfacorro]

• Uses maps instead of dict:dict().
• Avoid doing list processing when handling trace messages.
• Remove unnecessary list processing when building the iolist().
• Consolidate multiplications of 1000s into constants.
• Run the tracing for a maximum of DEFAULT_TIMEOUT to avoid getting a huge state in the tracer process (this can be modified so it can be provided as an option).
• Avoid having to generate multiple entries in the output by producing the format flamegraph.pl expects.

The result from this improvements is that eflame is now able to return a result for simple benchmarks and it doesn't timeout when it's waiting for the response of dump_bytes.